Did you know that the Pi 5 in 2024 received a firmware update that blocks people from soldering on larger ram chips?
However, this brings an element of risk to the user - the board hasn’t been tested by us - and is a potential support burden for us, with customers complaining of unreliable devices. We therefore remove the commercial incentive by locking devices to their original RAM size. And for improved compatibility with a variety of suppliers, we now also program in some other device attributes, meaning that switching parts of the same size may not work.
https://forums.raspberrypi.com/viewtopic.php?p=2380887#p2380888