Downgraded from Ventura to Big Sur now nothing works

So i downgraded from Ventura to big sur by creating a new drive and installing the old os on that one. Thing is i did a time machine backup when i still was on Ventura and now nothing works on big sur. i download apps and they wont start and the old ones i have dont work either, only some start... anyone have the same issue? what can i do to get everything running as normal on big sur? cant go back to ventura cause i caused alot of issues