Unity is a game engine that, for a long time, said "just pay us a monlthy fee to develop using our engine and we're square." then because EULAs and Terms of Service are slippery little bastards that are contracts but only benefit the owner they changed that to "Actually you're going to have to pay us a fee every time someone installs your game lol get rekt".
Lots of people are being 
about this, but, like, Marx did not fail to consider, and in Capitalism if you don't have a contract you have nothing. Signing a "contract" where one side can alter the terms to whatever they want seems... a bit naive but what you can you do?
Less that and more that they should understand enough about capitalism and business to know that getting totally fucked by the license holder was possible and even likely. The problem isn't them being upset, the problem is them being surprised.
There are a lot of open source engines, and a lot of non open source options that are better. Godot and Cryengine both come to mind.
A lot of people think it’s the old ‘ask for something way out of reality so your actual demand seems better by comparison’ tactic. Guess we’ll see.
I honestly can’t see this standing with genshin’s creator and Nintendo being as big and litigious as they are
