Hi,
it seems like you are speaking about users in your enviroment / company?
Please specify also:
- have you check the logs if so?
- have you have Conditional Access applied or security defaults?
- what exact applications are those?
- can you provide a screen shot? [ is it perhaps saying "your company requires to sign in again after some perviod of time / inactivity" ]
- Have you check / set up IDLE session logut after inactivity?
There might be sevral issues and dependencies but at first sight, if this is in regards to company enviroment i would check the SignIn Logs to check what conditional access control the session policy - and then in case would dig in a little bit further.