Sent email language is english not = to what I set in nextcloud

[Thatoo]

Describe the bug

If I do a poll (for example) and send invitation by email, the sent email will be in english like "Poll invitqtion" or "... invited you to take part in th epoll..." even though I have set the language to french and everything within nextcloud is indeed in french.

Context

• Hardware: Old laptop or computer
• YunoHost version: 4.1.8
• I have access to my server: Through SSH | through the webadmin | direct access via keyboard / screen
• Are you in a special context or did you perform some particular tweaking on your YunoHost instance?: no

Steps to reproduce

• make a poll in nextcloud (but the problem is the same with other apps)
• invite by email
• sent email is in english

Expected behavior

sent email would be in the same language as set in nextcloud settings