This is absolutely Unity's fault. If you buy a car to use Uber, and then half a year later Uber decides that your brand of car is no longer eligible to drive or that it needs to use a different fee structure, then it is Uber's fault that you are losing money.
If you launch an ad-supported game in 2020 under a revenue share and in 2023 Unity decides that it's bored of revenue shares and it wants you to start paying per install, it is Unity's fault that you are losing money. There just is no way to spin it otherwise. Are you seriously trying to blame developers right now for not being psychic?
I guarantee 100% that if we were having a conversation about Unity a year ago and someone said "I don't know if I should use Unity because what if they charge for installs in the future" you would have been making fun of that developer for having that concern. I promise you that a year ago you would not have predicted this change and you would have dismissed concerns about a theoretical structural change away from revenue shares as fearmongering.
> If I buy a Porsche in order to do Uber, it's not Uber's fault that I'm going to lose money.
Also once again, Unity's pricing model is not a natural consequence of the laws of physics. It's made up, Unity made it. The reason you'll lose money driving a porche for Uber is because the car will physically degrade, not because a bunch of board members at Uber got together and thought, "how can we extract more revenue from porsche owners?" Unity's revenue model is not the natural result of entropy, they decided to make it what it is.