Here’s an update: I may have somewhat narrowed it down to notes with pictures. I opened the Help vault and tried to reproduce it, but as you described it’s off little effect (just a tiny jump).
However, the moment I pasted some images in the Preview note, the jumps were bigger.
Edit: I noticed it is more frequent if the “Preview note” has a long bullet list.
If you can reproduce it this way, let me know. If not, I’ll upload my file asap. 