My macbook air keeps going to the login page

Hard to say what could be the cause of such random symptoms.

Usually a restart can help; because the system can do minor fixes

on restart; also you could run Safe mode, on restart. Then after it

runs in Safe awhile (may have to be sure that it starts up in Safe)

when later you want to no longer start in Safe, restart it normally.

• How to use Safe model on your Mac - Apple Support

https://support.apple.com/en-us/HT201262

This article suggests some of what Safe mode does; but most users

may not go as far as this suggests, to find even simple start in Safe

does some aspects of checking the system and repair some stuff.

For other non-invasive things; some symptoms could be resolved

by use of NRAM or PRAM reset; restart holding down 4 keys, etc.

If you experience issues with sleep, wake, power, charging your Mac

notebook battery, or other power-related symptoms, you might need

to reset the SMC (System Management Controller).

• Ways to back up or protect your files - Apple Support

https://support.apple.com/guide/mac-help/ways-to-back-up-or-protect-your-files-mh9052/mac

There also was a page I'd seen where it tells how to use Disk Utility..

• Disk Utility User Guide for Mac - Apple Support

..see How to repair a disk (Mac) drive; some instructions may go too far though.

Good luck & happy trails!🌞🎣