diff --git a/src/contentScripts/communityConsole/main.js b/src/contentScripts/communityConsole/main.js
index 637e061..309e41b 100644
--- a/src/contentScripts/communityConsole/main.js
+++ b/src/contentScripts/communityConsole/main.js
@@ -58,9 +58,6 @@
   // Canned response tags (for the "import CR" popup for the workflows feature)
   'ec-canned-response-row .tags',
 
-  // Thread page main content
-  'ec-thread > .page > .material-content > div[role="list"]',
-
   // Thread page reply section (for the thread page toolbar)
   kRepliesSectionSelector,
 
@@ -141,12 +138,6 @@
       window.TWPTWorkflowsImport.addButtonIfEnabled(node);
     }
 
-    // Inject old thread page design warning if applicable
-    if (node.matches(
-            'ec-thread > .page > .material-content > div[role="list"]')) {
-      window.TWPTThreadPageDesignWarning.injectWarningIfApplicable(node);
-    }
-
     // Inject thread toolbar
     if (threadToolbar.shouldInject(node)) {
       threadToolbar.injectIfApplicable(node);
@@ -208,8 +199,7 @@
   flattenThreads = new FlattenThreads();
   reportDialogColorThemeFix = new ReportDialogColorThemeFix(options);
 
-  // threadPageDesignWarning and workflowsImport are
-  // initialized in start.js
+  // workflowsImport is initialized in start.js
 
   // Before starting the mutation Observer, check whether we missed any
   // mutations by manually checking whether some watched nodes already
diff --git a/src/contentScripts/communityConsole/start.js b/src/contentScripts/communityConsole/start.js
index 063f58a..cc54540 100644
--- a/src/contentScripts/communityConsole/start.js
+++ b/src/contentScripts/communityConsole/start.js
@@ -2,15 +2,11 @@
 import {getOptions} from '../../common/optionsUtils.js';
 
 import FlattenThreadsReplyActionHandler from './flattenThreads/replyActionHandler.js';
-import ThreadPageDesignWarning from './threadPageDesignWarning.js';
 import WorkflowsImport from './workflows/import.js';
 
-const SMEI_RCE_THREAD_INTEROP = 22;
-
 getOptions(null).then(options => {
   /* IMPORTANT NOTE: Remember to change this when changing the "ifs" below!! */
-  if (options.loaddrafts || options.interopthreadpage ||
-      options.fixpekb269560789) {
+  if (options.fixpekb269560789) {
     var startup =
         JSON.parse(document.querySelector('html').getAttribute('data-startup'));
 
@@ -20,31 +16,12 @@
       }
     }
 
-    if (options.loaddrafts) {
-      startup[4][13] = true;
-    }
-
-    if (options.interopthreadpage) {
-      var index = startup[1][6].indexOf(SMEI_RCE_THREAD_INTEROP);
-
-      switch (options.interopthreadpage_mode) {
-        case 'previous':
-          if (index > -1) startup[1][6].splice(index, 1);
-          break;
-
-        case 'next':
-          if (index == -1) startup[1][6].push(SMEI_RCE_THREAD_INTEROP);
-          break;
-      }
-    }
-
     document.querySelector('html').setAttribute(
         'data-startup', JSON.stringify(startup));
   }
 
   // Initialized here instead of in main.js so the first event is received if it
   // happens when the page loads.
-  window.TWPTThreadPageDesignWarning = new ThreadPageDesignWarning();
   window.TWPTWorkflowsImport = new WorkflowsImport();
 
   if (options.ccdarktheme) {
diff --git a/src/contentScripts/communityConsole/threadPageDesignWarning.js b/src/contentScripts/communityConsole/threadPageDesignWarning.js
deleted file mode 100644
index 155d916..0000000
--- a/src/contentScripts/communityConsole/threadPageDesignWarning.js
+++ /dev/null
@@ -1,162 +0,0 @@
-import {MDCTooltip} from '@material/tooltip';
-import {waitFor} from 'poll-until-promise';
-
-import {parseUrl} from '../../common/commonUtils.js';
-import {injectStylesheet} from '../../common/contentScriptsUtils.js';
-import {getDocURL} from '../../common/extUtils.js';
-import {getOptions} from '../../common/optionsUtils.js';
-
-import {createExtBadge} from './utils/common.js';
-
-const kSMEINestedReplies = 15;
-const kViewThreadResponse = 'TWPT_ViewThreadResponse';
-
-export default class ThreadPageDesignWarning {
-  constructor() {
-    this.lastThread = {
-      body: {},
-      id: -1,
-      timestamp: 0,
-    };
-    this.setUpHandler();
-
-    // We have to save whether the old UI was enabled at startup, since that's
-    // the moment when it takes effect. If the option changes while the tab is
-    // open, it won't take effect.
-    getOptions([
-      'interopthreadpage', 'interopthreadpage_mode'
-    ]).then(options => {
-      this.shouldShowWarning = options.interopthreadpage &&
-          options.interopthreadpage_mode == 'previous';
-
-      if (this.shouldShowWarning) {
-        injectStylesheet(
-            chrome.runtime.getURL('css/thread_page_design_warning.css'));
-      } else {
-        this.removeHandler();
-      }
-    });
-
-    this.isExperimentEnabled = this.isNestedRepliesExperimentEnabled();
-  }
-
-  isNestedRepliesExperimentEnabled() {
-    if (!document.documentElement.hasAttribute('data-startup')) return false;
-
-    let startup =
-        JSON.parse(document.documentElement.getAttribute('data-startup'));
-    return startup?.[1]?.[6]?.includes?.(kSMEINestedReplies);
-  }
-
-  eventHandler(e) {
-    if (e.detail.id < this.lastThread.id) return;
-
-    this.lastThread = {
-      body: e.detail.body,
-      id: e.detail.id,
-      timestamp: Date.now(),
-    };
-  }
-
-  setUpHandler() {
-    window.addEventListener(kViewThreadResponse, this.eventHandler.bind(this));
-  }
-
-  removeHandler() {
-    window.removeEventListener(
-        kViewThreadResponse, this.eventHandler.bind(this));
-  }
-
-  injectWarning(content) {
-    let div = document.createElement('div');
-    div.classList.add('TWPT-warning');
-
-    let icon = document.createElement('material-icon');
-    icon.classList.add('TWPT-warning--icon');
-
-    let iconContent = document.createElement('i');
-    iconContent.classList.add('material-icon-i', 'material-icons-extended');
-    iconContent.setAttribute('role', 'img');
-    iconContent.setAttribute('aria-hidden', 'true');
-    iconContent.textContent = 'warning';
-
-    icon.append(iconContent);
-
-    let text = document.createElement('div');
-    text.classList.add('TWPT-warning--text');
-    text.textContent =
-        chrome.i18n.getMessage('inject_threadpagedesign_warning');
-
-    let btn = document.createElement('a');
-    btn.classList.add('TWPT-warning--btn');
-    btn.href =
-        getDocURL('features.md#Thread-page-design-in-the-Community-Console');
-    btn.setAttribute('target', '_blank');
-    btn.setAttribute('rel', 'noopener noreferrer');
-
-    const [badge, badgeTooltip] = createExtBadge();
-
-    let btnText = document.createElement('div');
-    btnText.textContent = chrome.i18n.getMessage('btn_learnmore');
-
-    btn.append(badge, btnText);
-
-    div.append(icon, text, btn);
-    content.prepend(div);
-
-    new MDCTooltip(badgeTooltip);
-  }
-
-  injectWarningIfApplicable(content) {
-    return waitFor(
-               () => {
-                 if (this.shouldShowWarning === undefined)
-                   return Promise.reject(
-                       new Error('shouldShowWarning is not defined.'));
-
-                 return Promise.resolve({result: this.shouldShowWarning});
-               },
-               {
-                 interval: 500,
-                 timeout: 10 * 1000,
-               })
-        .then(preShouldShowWarning => {
-          if (!preShouldShowWarning.result) return;
-
-          // If the global SMEI experiment is enabled, all threads use nested
-          // replies, so we'll skip the per-thread check and always show the
-          // warning banner.
-          if (this.isExperimentEnabled) return Promise.resolve({result: true});
-
-          let currentThread = parseUrl(location.href);
-          if (currentThread === false)
-            throw new Error('current thread id cannot be parsed.');
-
-          return waitFor(() => {
-            let now = Date.now();
-            let lastThreadInfo = this.lastThread.body['1']?.['2']?.['1'];
-            if (now - this.lastThread.timestamp > 30 * 1000 ||
-                lastThreadInfo?.['1'] != currentThread.thread ||
-                lastThreadInfo?.['3'] != currentThread.forum)
-              throw new Error(
-                  'cannot obtain information about current thread.');
-
-            // If the messageOrGap field contains any items, the thread is using
-            // nested replies. Otherwise, it probably isn't using them.
-            return Promise.resolve(
-                {result: this.lastThread.body['1']?.['40']?.length > 0});
-          }, {
-            interval: 500,
-            timeout: 10 * 1000,
-          });
-        })
-        .then(shouldShowWarning => {
-          if (shouldShowWarning.result) this.injectWarning(content);
-        })
-        .catch(err => {
-          console.error(
-              '[threadPageDesignWarning] An error ocurred while trying to decide whether to show warning: ',
-              err);
-        });
-  }
-}