There's very little reason not to upgrade from Java 8 at this point. Everything should be a drop-in replacement and there are significant performance benefits (garbage collection is leagues better) to doing so.
The bigger problem is that a lot of places are stuck on Oracle JDK - 8u252 is the last free version so a lot of places just decided they'd never upgrade, nor do they want to look at whether Temurin or Coretto would work for them (the answer is usually yes).
The bigger problem is that a lot of places are stuck on Oracle JDK - 8u252 is the last free version so a lot of places just decided they'd never upgrade, nor do they want to look at whether Temurin or Coretto would work for them (the answer is usually yes).