But the underlying problem here is even bigger than unity's shitty practices - it means you can change your ToS at any point, at any time, without notice, without the need of consent, and the user has nothing to do about it.

Basically, the user agrees to a certain contract, that the other party can just silently change at any time, and if this is applicable in court, we are screwed.

What if visual studio suddenly added a line in their ToS "we have full rights to any code you ever write in VS" and they suddenly own your 10 years old project? What if android just silently added "we can take pictures of you from your front camera and sell them to porn sites".

How the hell is it possible you can change the ToS without any notice or consent?

Everything is allowed if you have enough money