I assume you mean this announcement: https://blog.unity.com/news/plan-pricing-and-packaging-updates
I think it's fair. Unity is still giving a lot for free. Remember, it's not only the installs, it's the installs and money you earn combined. So free games will be exempt, because they will have the installs but not the money component.
If you compare it to GameMaker, GameSalad, Clickteam Fusion, Construct - you pay an upfront fee and then again for new releases. So over a few years you might not make money from your games, but you're paying for the software. With Unity, you only start paying once you start earning.
Unreal charges a percentage of takings and it isn't capped (last time I checked). So they will coin it, if your game becomes popular.
I had played around with Godot a few years ago but it wasn't suited to the way I work - it kept crashing and losing my data. I'm sure it's improved since then, but I'm not going to risk it. Besides, the community must pay for it so the developers can continue its development. So although payment is voluntary, it isn't exactly free.