The patch notes for 20w22a mentioned an experimental rendering changes.
-Between 20w21a and 20w22a my framerate ( ? ) dropped significantly. (Seriously laggy, blocks would take a few seconds to break after the breaking animation finished, and the view was jerky when trying to look around)
-I changed in-game graphics settings to be as basic as possible (no clouds, fast graphics, render distance of 2 chunks, no smooth lighting) which failed to fix the problem.

So, all in all, I concluded it probably had to do with the latest snapshot.