I'm not sure which snapshot exactly it happened but one of the middle stage 1.19 snapshots made my witch farm stop spawning witches. It now spawns only from the normal mob pool. 

It's very upsetting as I have spent 100's how hours working on that area based around that witch farm.

EDIT: (05/26/22)

Here is a link to a google drive with my save file

https://drive.google.com/file/d/1Ngh4NrWiGzA2TqrDkGSaM8ezY118btwN/view?usp=sharing