21 was pretty shit for me since it continued the Heidi and Trump-Garrison plots but:
Put it Down (aged badly)
Hummels and Heroin
Super Hard PCNess (maybe)
ManBearPig duo (Time to Get Cereal/Nobody Got Cereal)
The first three episodes this season were pretty bad, but every episode since that has been pretty good, except for Buddha Box which was mediocre.>>104634149
As I said, Season 21 continued the Heidi and Trump-Garrison subplot. It tried to not be serialized but it clearly failed.
Season 22 on the other hand just has continuity in the background and meta references to previous episodes. Each episode has it's own plot otherwise and nothing really gets in the way. Similar to season 18. Buddha Box does continue the PC Principal plot from The Problem with A Poo, but that's about it.