Unity is coming out with a new pricing model for 2024, where game developers will have to fork over money every time someone installs their game. this includes redownloads of already bought games, and downloads of games from places like game pass. it also applies to game demos and free games. it even applies if someone transfers a game from one device to another.
the policy applies if your company makes over $200,000 in yearly revenue and the game has been downloaded over a certain number of times in its entire lifetime.
there are rumors that gambling games and gotcha games are exempt.
https://blog.unity.com/news/plan-pricing-and-packaging-updates
First sale would seem to prohibit them from charging for reinstalls. At least as far as you at home. They can play with the developers however they want since those are agreements that need to be ongoing and some will start in the future after the license change. I don't think they're going to alter existing deals unless a dev upgrades versions.