I have been using PE 15 for the last few years and I periodically investigate if/when it would be useful to upgrade. It's strictly for personal, non-professional use so I'm not thinking of Premiere Pro. I'm not very interested in any gimmicky things, just basic video editing capability.
For example, I note that Adobe is featuring shadow and highlight adjustments in its promotional material for 2022. That's of course also in 15, but have they improved the methods? Also, I find that shake reduction in 15 is not usually very helpful, sometimes making things worse. Has that been improved over the last few years? Things like that.