diff --git a/.changeset/kind-schools-rule.md b/.changeset/kind-schools-rule.md
new file mode 100644
index 000000000..f2344f9a3
--- /dev/null
+++ b/.changeset/kind-schools-rule.md
@@ -0,0 +1,22 @@
+---
+'@web/test-runner-chrome': patch
+---
+
+This changeset removes the Puppeteer/Chrome focus browser patches that shouldn't
+be needed anymore, and can cause instability.
+
+The patches were added quite a while ago, and the upstream issues should
+be resolved in Chromium. See: https://issues.chromium.org/issues/40272146.
+
+Also see:
+https://github.com/puppeteer/puppeteer/issues/10350#issuecomment-1586858101.
+
+The patches are currently also resulting some instability of web test
+runner. That is because the patch calls an exposed function from inside
+the browser, while navigation later on during `stopSession` can happen;
+breaking the handle for retrieving function call arguments passed to the
+exposed function.
+
+Puppeteer team found this issue and also landed a fix to improve the
+failure mode here. See:
+https://github.com/puppeteer/puppeteer/pull/13759
diff --git a/.changeset/shaggy-chefs-dance.md b/.changeset/shaggy-chefs-dance.md
new file mode 100644
index 000000000..1ba084713
--- /dev/null
+++ b/.changeset/shaggy-chefs-dance.md
@@ -0,0 +1,10 @@
+---
+'@web/test-runner-core': patch
+---
+
+Improve debug message for test runner uncaught exceptions
+
+This should make debugging easier. It wasn't very easy to figure out
+where the errors originated from (because of how the actual uncaught
+exception only happened with many concurrent builds inside a sandbox
+environment that is hard to debug).
diff --git a/package-lock.json b/package-lock.json
index ea5bd2f01..b0ffe701d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9903,15 +9903,6 @@
         "node": ">=0.8.0"
       }
     },
-    "node_modules/async-mutex": {
-      "version": "0.4.0",
-      "resolved": "https://registry.npmjs.org/async-mutex/-/async-mutex-0.4.0.tgz",
-      "integrity": "sha512-eJFZ1YhRR8UN8eBLoNzcDPcy/jqjsg6I1AP+KvWQX80BqOSW1oJPJXDylPUEeMr2ZQvHgnQ//Lp6f3RQ1zI7HA==",
-      "license": "MIT",
-      "dependencies": {
-        "tslib": "^2.4.0"
-      }
-    },
     "node_modules/asynckit": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/asynckit/-/asynckit-0.4.0.tgz",
@@ -38780,7 +38771,6 @@
       "dependencies": {
         "@web/test-runner-core": "^0.13.0",
         "@web/test-runner-coverage-v8": "^0.8.0",
-        "async-mutex": "0.4.0",
         "chrome-launcher": "^0.15.0",
         "puppeteer-core": "^24.0.0"
       },
diff --git a/packages/test-runner-chrome/package.json b/packages/test-runner-chrome/package.json
index 1fc6f739b..2159f9636 100644
--- a/packages/test-runner-chrome/package.json
+++ b/packages/test-runner-chrome/package.json
@@ -48,7 +48,6 @@
   "dependencies": {
     "@web/test-runner-core": "^0.13.0",
     "@web/test-runner-coverage-v8": "^0.8.0",
-    "async-mutex": "0.4.0",
     "chrome-launcher": "^0.15.0",
     "puppeteer-core": "^24.0.0"
   },
diff --git a/packages/test-runner-chrome/src/ChromeLauncherPage.ts b/packages/test-runner-chrome/src/ChromeLauncherPage.ts
index cf5cfebe5..aa4862f40 100644
--- a/packages/test-runner-chrome/src/ChromeLauncherPage.ts
+++ b/packages/test-runner-chrome/src/ChromeLauncherPage.ts
@@ -2,9 +2,6 @@ import { Page, JSCoverageEntry } from 'puppeteer-core';
 import { TestRunnerCoreConfig } from '@web/test-runner-core';
 import { v8ToIstanbul } from '@web/test-runner-coverage-v8';
 import { SessionResult } from '@web/test-runner-core';
-import { Mutex } from 'async-mutex';
-
-const mutex = new Mutex();
 
 declare global {
   interface Window {
@@ -49,43 +46,6 @@ export class ChromeLauncherPage {
       });
     }
 
-    // Patching the browser page to workaround an issue in the new headless mode of Chrome where some functions
-    // with callbacks (requestAnimationFrame and requestIdleCallback) are not executing their callbacks.
-    // https://github.com/puppeteer/puppeteer/issues/10350
-    if (!this.patchAdded) {
-      await this.puppeteerPage.exposeFunction('__bringTabToFront', (id: string) => {
-        const promise = new Promise(resolve => {
-          this.resolvers[id] = resolve as () => void;
-        });
-        return mutex.runExclusive(async () => {
-          await this.puppeteerPage.bringToFront();
-          await promise;
-        });
-      });
-      await this.puppeteerPage.exposeFunction('__releaseLock', (id: string) => {
-        this.resolvers[id]?.();
-      });
-      await this.puppeteerPage.evaluateOnNewDocument(() => {
-        // eslint-disable-next-line @typescript-eslint/ban-types
-        function patchFunction(name: string, fn: Function) {
-          (window as any)[name] = (...args: unknown[]) => {
-            const result = fn.call(window, ...args);
-            const id = Math.random().toString().substring(2);
-            // Make sure that the tab running the test code is brought back to the front.
-            window.__bringTabToFront(id);
-            fn.call(window, () => {
-              window.__releaseLock(id);
-            });
-            return result;
-          };
-        }
-
-        patchFunction('requestAnimationFrame', window.requestAnimationFrame);
-        patchFunction('requestIdleCallback', window.requestIdleCallback);
-      });
-      this.patchAdded = true;
-    }
-
     await this.puppeteerPage.setViewport({ height: 600, width: 800 });
     await this.puppeteerPage.goto(url);
   }
diff --git a/packages/test-runner/src/startTestRunner.ts b/packages/test-runner/src/startTestRunner.ts
index a22757561..5214691ba 100644
--- a/packages/test-runner/src/startTestRunner.ts
+++ b/packages/test-runner/src/startTestRunner.ts
@@ -73,7 +73,7 @@ export async function startTestRunner(options: StartTestRunnerParams = {}) {
     if (autoExitProcess) {
       process.on('uncaughtException', error => {
         /* eslint-disable-next-line no-console */
-        console.error(error);
+        console.error(`Uncaught exception, stopping test runner..\n`, error);
         stop();
       });
     }