Raspberry Pi is actively preventing enthusiasts from upgrading soldered memory to a larger configuration even when the replacement chip is technically compatible. The company says the restriction is intended to discourage unofficial high-capacity resales.
The solution to this decidedly rare problem is authorized resellers, not an arbitrary block on a very technically demanding upgrade.
That’s assuming this is the actual problem though. If the problem is actually “We want to make more money by charging extra for ‘enthusiast models’” then this is the correct tactic to ensure that you aren’t undercut by cheap labor.