Some developers are seriously considering de-listing their games from online shops when the Unity Runtime Fee kicks off at the start of next year, meaning some titles built on Unity could end up being temporarily — or permanently — unavailable. Here's what developers are saying about the Unity Runtime Fee on social media, and what games could be impacted.
Retroactive change of terms for already released unchanged products? I don’t know the legal details but it seems pretty strange that they can just say they will charge over something for products that were finished and released under different terms before all this. The devs may not even be opening those projects on Unity anymore.
There’s nothing implicit about “opening the project in unity” that needs to be a trigger for terms to change.
If you make and distribute a game made in unity, then you are distributing some unity IP. You would need the license holder to grant you permission to do that. The terms you agree to with unity are what grant you the right to distribute this.
So this has very little to do with “have you opened the editor lately”, and is more similar to when e.g. Dead By Daylight has to stop selling a dlc character because they don’t renew an agreement with the rights holders.