I see this being repeated over and over, but I'm not really understanding, say an indie Dev makes 500k in revenue in one year, how much is it going to unity? If it is anything below 50k it seems to me like a sweet deal for all the things Unity offers to devs.
There's no shortage of free and good game engines out there, but I guess Unity does offer a lot that those free options don't.
All of those counted as a new install, and this was stated to be intentional by unity to all the journalists who reached out and by their internal developers on the support forum.
So the long tail of things like your customers buying a new phone == old apps get transferred == that counts as a new install and you get charged. Reinstall a game from steam or change the install drive or directory? Same thing.
Beyond devs and game types that are affected by legitimate usage, there is the clear problem of malicious installs (what a phrase) and abuse. Unity's answer to that was that proprietary secret internal models would solve abuse, but also that developers would have to reach out with proof of being falsely billed after it happened. And just kinda hope that unity would have the support and billing staff to ever actually deal with that problem.