I'm going to use the Personal / Plus pricing instead of Pro, on a f2p mobile game, but let's say you made 200k$ on the first 200k install, but only 20k$ on the next 200k installs (for whatever reason, different market, whale spending 10's of thousands $ skewing the data, etc.), you owe Unity 40k$ and are now in the negative for those new installs when you could've still turned a profit, albeit less.

Of course Unity deserve to be paid and receive revenue, I'm absolutely not against that and if you are on the Pro subscription, it is only a concerned once you reach 1M$ which at this point means the project should be profitable and manage to pay that tax (otherwise maybe that project isn't commercially viable).

But it just feel very harsh for the mega popular indie hit that have very low revenue per user you know... A % of revenue would be better or at the very least only count install that generated revenue or whatever...