Hey,
I run a Nextcloud (Version 29.0.4) on a LCMP (Linux, Caddy, MySQL/MariaDB, PHP) stack on a Debian 12 server and found following possible bug.
Mails from a Discourse instance are displayed in their HTML version unreadable and the Mail app defaults to displaying the HTML version of said app.
On dark mode:
On light mode:
Noted: This can be also a bug on the side of Discourse. Other mail applications and webmailer like SOGo are displaying the mails correctly.
Example SOGo:
