I can only replicate cursor jumps with alphabetical characters. The cursor can jump multiple characters depending on typing speed, which seems similar to the upstream CodeMirror issue. See these tests from a new note:
Typing # a then typing another header elsewhere stops cursor jumps for only the new header's first word.
Typing > a doesn't cause cursor jumps.
Typing >a doesn't stop cursor jumps on other lines.
Typing - a stops cursor jumps after typing - a or >a on other lines.
Typing >a or - a then removing it doesn't stop cursor jumps.
Workarounds
This Github issue states that adding new line characters at end of note stops cursor jumps. I can only reliably replicate this by triggering a cursor jump and preserving that text, only for typing bullets with -.
I use another editor then paste text into Joplin once finished. If you want to continue using Joplin, use or emulate plain text which seemingly isn't affected by this bug:
For quotes, use > a instead of >a.
For headers, skip the space after the # then add it later.
For bullets, use *, a numbered list, or skip the space after the - then add it later.
I had a similar issue with the OpenBoard keyboard (in Android Joplin v3.0.3) which almost stopped completely when I switched to Simple Keyboard. Now this only happens to me in settings text boxes.
EDIT: I'll admit that I'm having a hard time reproducing the editor cursor jumps now, with/out plugins. But the text boxes in the settings are still an issue.
EDIT2: OK, so while editing this happens to me in RTL languages (with OpenBoard) but not in English (my Android 13 system language). In settings text boxes this happens to me while typing in English (in 5 different keyboards, including Samsung and Gboard).
.