Mobile Mattermost app bug : Too many follow-up request : 21

My YunoHost server

Hardware: VPS bought online
YunoHost version: 11.2.11.3 (stable & up to date)
I have access to my server : Through SSH & webadmin
Are you in a special context or did you perform some particular tweaking on your YunoHost instance ? : no
If your request is related to an app, specify its name and version: 9.7.1~ynh1

Description of my issue:

When I try to install the Mattermost mobile app on my new phone, it doesn’t work anymore. The web app functions without any issues, and the diagnostic test on Yunohost also reports no problems.

On the initial page, I encounter the following message:

Too many follow-up requests: 21

Do you have any ideas on what I should do?

Thank you,

Thomas."

Trop d’attaques du serveur ?