Hi @dorianrevest83,
It’s very odd indeed!
Try to reinstall emails via the BP tools (Tools > BuddyPress > Reinstall emails – delete and restore from defaults -) .
Be careful because this will delete and rebuild all your BP email templates.
If it doesn’t change anything, I advise you to deactivate any BuddyPress add-ons to check for possible incompatibility or directly reach the BuddyPress plugin author.
Hope this will help!
Best regards,