You need to connect your phone to Samsung Smartswitch on a PC and reinstall Android 13 also I believe this will erase all your data from your device so make sure you back it up
You will need to connect the phone with the Smart Switch software on a pc to downgrade back to One UI 5. I would also suggest you backup up the phone using Smart Switch before you do downgrade the OS as it will wipe the phone and install a fresh OS.