diff --git a/components/ai_chat/core/browser/engine/remote_completion_client_unittest.cc b/components/ai_chat/core/browser/engine/remote_completion_client_unittest.cc
index 35c7a82dd91..95cc33f00ea 100644
--- a/components/ai_chat/core/browser/engine/remote_completion_client_unittest.cc
+++ b/components/ai_chat/core/browser/engine/remote_completion_client_unittest.cc
@@ -68,16 +68,12 @@ TEST_F(RemoteCompletionClientUnitTest, ParseJson) {
   run_loop2.Run();
 
   // This test verifies that the callback is not called when the response is
-  // "[DONE]". We use a run loop to wait for the callback to be called, and we
-  // expect it to never be called. Therefore, we use RunUntilIdle() instead of
-  // Run(), since Run() would time out waiting for the callback to be called.
-  base::RunLoop run_loop3;
+  // "[DONE]". We use RunUntilIdle() to wait for the callback to be called, and
+  // we expect it to never be called.
   SendMesage(
-      base::BindRepeating([](base::RunLoop* run_loop,
-                             const std::string& response) { run_loop->Quit(); },
-                          &run_loop3),
+      base::BindRepeating([](const std::string& response) { ADD_FAILURE(); }),
       "data: [DONE]");
-  run_loop3.RunUntilIdle();
+  task_environment_.RunUntilIdle();
 }
 
 }  // namespace ai_chat
diff --git a/components/api_request_helper/api_request_helper_unittest.cc b/components/api_request_helper/api_request_helper_unittest.cc
index 3dc4e50a4de..b09559aa4a8 100644
--- a/components/api_request_helper/api_request_helper_unittest.cc
+++ b/components/api_request_helper/api_request_helper_unittest.cc
@@ -138,10 +138,8 @@ TEST_F(ApiRequestHelperUnitTest, SanitizedRequest) {
   SendRequest("{", base::Value());
   SendRequest("0", base::Value());
   SendRequest("a", base::Value());
-  // Android's sanitizer doesn't support trailing commas.
-#if !BUILDFLAG(IS_ANDROID)
-  SendRequest("{\"a\":1,}", ParseJson("{\"a\":1}"));
-#endif
+  // The sanitizer doesn't support trailing commas by default.
+  SendRequest("{\"a\":1,}", base::Value());
 }
 
 TEST_F(ApiRequestHelperUnitTest, RequestWithConversion) {
@@ -245,28 +243,21 @@ TEST_F(ApiRequestHelperUnitTest, SSEJsonParsing) {
   run_loop2.Run();
 
   // This test verifies that the callback is not called when the response is
-  // "[DONE]". We use a run loop to wait for the callback to be called, and
-  // we expect it to never be called.
-  base::RunLoop run_loop3;
-  SendMessageSSEJSON("data: [DONE]",
-                     base::BindRepeating(
-                         [](base::RunLoop* run_loop,
-                            data_decoder::DataDecoder::ValueOrError result) {
-                           run_loop->Quit();
-                         },
-                         &run_loop3));
-  run_loop3.RunUntilIdle();
+  // "[DONE]".
+  SendMessageSSEJSON(
+      "data: [DONE]",
+      base::BindRepeating([](data_decoder::DataDecoder::ValueOrError result) {
+        ADD_FAILURE();
+      }));
+  task_environment_.RunUntilIdle();
 
   // Testing with no JSON and an empty string
-  base::RunLoop run_loop4;
-  SendMessageSSEJSON("",
-                     base::BindRepeating(
-                         [](base::RunLoop* run_loop,
-                            data_decoder::DataDecoder::ValueOrError result) {
-                           run_loop->Quit();
-                         },
-                         &run_loop4));
-  run_loop4.RunUntilIdle();
+  SendMessageSSEJSON(
+      "",
+      base::BindRepeating([](data_decoder::DataDecoder::ValueOrError result) {
+        ADD_FAILURE();
+      }));
+  task_environment_.RunUntilIdle();
 }
 
 }  // namespace api_request_helper
diff --git a/components/brave_wallet/browser/wallet_data_files_installer_unittest.cc b/components/brave_wallet/browser/wallet_data_files_installer_unittest.cc
index 313aeb243fa..02004be5c70 100644
--- a/components/brave_wallet/browser/wallet_data_files_installer_unittest.cc
+++ b/components/brave_wallet/browser/wallet_data_files_installer_unittest.cc
@@ -257,6 +257,7 @@ TEST_F(WalletDataFilesInstallerUnitTest, OnDemandInstallAndParsing_EmptyPath) {
       .Times(1)
       .WillOnce(testing::Return(true));
   SetOnDemandUpdateCallbackWithComponentReady(base::FilePath());
+  RunUntilIdle();
   CreateWallet();
 
   RunUntilIdle();