@Benoit-NL As wgarcia mentions, the other browsers are in alpha or beta versions at the moment, but I use them as a supplement to be able to us UT as my main phone. Some to look up in OpenStore:
Mimi Browser
uWolf.
Sapot
You can also check out the Firefox click, which has to be manually downloaded from gitlab and then installed. https://gitlab.com/debclick/uFirefox/-/jobs/9866929411/artifacts/browse/build/aarch64-linux-gnu/app/ .
As for FP5-specific bug reports, these can be sent here: https://gitlab.com/ubports/porting/reference-device-ports/android11/fairphone-5/fairphone-fp5/-/issues/?sort=created_date&state=opened&first_page_size=100. Just check first if the bug has already been reported.
Another possible solution to your problem is using the UT native e-mail app Dekko, where you would have to add your Mailo-account through imap or some other technology.
I recommend joining the Telegram groups.