Hi,
since having updated to version 9 (or core 5 respectively), login attempts lead to a 502 error. Logout, too, causes a 502.
Only with the core plugin deactivated from FTP I can login, then reactivate it and proceed at front and backend without problems, until logout.
Plugins that could affect login are currently deactivated, except Woocommerce.
Thank you,
Best regards
Martin