How to restaure old version after update

I make update but i have this message "Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 8.1.0"."

i can't change my PHP version because others application run on my PHP 8.0 version

I would like to restaure old version

Sorry, you can't do a downgrade because the database structure changes during the upgrade. However, I don't think that's the best plan of attack. Most hosting environments allow you to set PHP version by domain or by account. I would recommend trying that first. If in the worst case a downgrade is the only option then you have to restore from backup. If you didn't do a backup before upgrading, then you'll need to check with your hosting environment to see if an auto backup was done - again, most hosts do this. In that case, you'll only lose the data that's accumulated since the backup.

Is downgrade possible if you dont mind resetting your database?