Hi there request you to follow the below steps:
1. Check your phone for latest software version.
2. Go to Free Fire App settings and see if all the required permissions are granted.
3. Clear cache & storage of the App after backing up & disable/re-enable the App.
4. Try the same under safe mode:
Hold the power button for 5 seconds => When the screen flashes with option => Press & hold power option => You will get an option to restart in safe mode
5. If still you face the issue factory reset your phone after taking a full backup:
https://www.asus.com/support/FAQ/1006346/