At the $dayjob, writing some python assuming late model 3.10.x, and discovering that the API has changed when I have to make sure it works on 3.6.x and 3.7.x.
Nevermind important libraries like pandas changing the API so some functions you 've used for years just disappear.
I've got 30+ year old perl 5, that just works. And is readable. I wish 2 year old python could just work.