Android devices logout issue
Recently some android devices (Samsung galaxy S20/21) has battery optimization feature which prevents the app running at back stage. So it will have logout issue.
If you smart phone do have this feature, please disable the battery optimization and deep sleep mode in the installation. Put unused apps to sleep.
Check this article for turning off battery optimization
Check this article for turning off battery optimization for putting unused apps to sleep.
Then close all the apps and reboot your phone to see if it works.