Deletion of multiple E-Mails is freezing the Google Chrome Tab where NC Mail is open

Steps to reproduce

1. Go to you NC Mail Inbox
2. Select two or more Emails by clicking on the icons infront the sender name so a tick shows
3. Click on the trash bin icon showing up on top of your mail list where it says "Delete 2 Threads"

Expected behavior

To just delete all the selected threads and operate as normal

Actual behavior

The browser tab becomes inoperable and I am getting a browser message if I want to wait for the server or quit.
Reload will not help, I have to close the Browser Tab, go back to the NC Dashboard and then click on Mail again to get it back working, however it has deleted the selected threats.

Mail app version

4.3.1

Nextcloud version

30.0.4

Mailserver or service

Dovecot

Operating system

No response

PHP engine version

None

Nextcloud memory caching

No response

Web server

None

Database

None

Additional info

Log Message shows:
{"reqId":"vrlxLJCg1O92Z5vIn2jF","level":3,"time":"2025-03-20T08:19:13+00:00","remoteAddr":"37.24.88.121","user":"bb7ab886-e8d7-1038-8011-175fa2481ab1","app":"mail","method":"GET","url":"/index.php/apps/mail/api/messages/134041/smartreply","message":"Smart reply failed: Failed to decode smart replies JSON output","userAgent":"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36","version":"30.0.4.1","exception":{"Exception":"OCA\Mail\Exception\ServiceException","Message":"Failed to decode smart replies JSON output","Code":1,"Trace":[{"file":"/var/www/nextcloud/apps/mail/lib/Controller/MessagesController.php","line":892,"function":"getSmartReply","class":"OCA\Mail\Service\AiIntegrations\AiIntegrationsService","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":208,"function":"smartReply","class":"OCA\Mail\Controller\MessagesController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":114,"function":"executeController","class":"OC\AppFramework\Http\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":161,"function":"dispatch","class":"OC\AppFramework\Http\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":302,"function":"main","class":"OC\AppFramework\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1003,"function":"match","class":"OC\Route\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":24,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/apps/mail/lib/Service/AiIntegrations/AiIntegrationsService.php","Line":272,"message":"Smart reply failed: Failed to decode smart replies JSON output","exception":[],"CustomMessage":"Smart reply failed: Failed to decode smart replies JSON output"},"id":"67dbd0ca6d027"}

Start by reproducing the multi-thread deletion steps in NC Mail 4.3.1 with Chrome and inspect whether the browser request remains pending. The log mentions MessagesController.php and AiIntegrationsService.php, but its smart-reply error may be unrelated; done means deleting multiple selected threads without making the Mail tab inoperable.