Firmware password
I bought this MacBook Pro in 2021 and I lost contact with the owner, recently it asked me for a firmware password after mistakenly entering a wrong password and I don’t have the firmware password
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Then it is impossible to remove the firmware lock. If you have the necessary proof of purchase/ownership and proper ID, then Apple or an AASP will remove the firmware lock, but being a preowned device you won't have the necessary proof of purchase. This is one of the dangers of purchasing a used Mac. It also means the previous owner did not properly prepare the Mac for sale and you also decided not to perform a clean install of macOS which would have easily revealed the firmware lock while you still had contact with the previous owner. As long as the computer can still boot to the internal drive you can use the computer as usual, but if the internal drive becomes unbootable, then you have a brick.
If you have a 2018+ Mac, then you could try "Restoring" the firmware to see if it will remove the firmware lock. I have no idea if it will work, but this procedure will destroy all data on the computer.
Revive or restore an Intel-based Mac using Apple Configurator - Apple Support
Revive or restore a Mac with Apple silicon using Apple Configurator - Apple Support
Here is an Apple article regarding the firmware lock:
Set a firmware password on your Mac - Apple Support