IssueTracker

Room has support for RxJava 2 but since RxJava 3 is out, RxJava 2 is now in maintenance mode and it'll be supported until February 28, 2021. RxJava 3 is not as big update as RxJava 2 was so I think it may not be a lot of work to support it in Room.

From Room point of view I think the biggest difference is new package structure: https://github.com/ReactiveX/RxJava/wiki/What's-different-in-3.0#package-structure

Not sure if it affects Room but RxJava 3 supports Java 8:
https://github.com/ReactiveX/RxJava/wiki/What's-different-in-3.0#java-8

RxJava 3 can live next to RxJava 2 in a project and there is an interop library that  helps with making them work together: https://github.com/ReactiveX/RxJava/wiki/What's-different-in-3.0#rxjava-2x
but I think that it would still be good to have direct RxJava 3 support in Room to make the adoption of RxJava 3 faster.