What you have to do when updating is to set “Update notes” and “Update notetypes” to “Always”. Also check “Merge notetypes” in case you might have changed it.
After importing you should see a message like:
- 537 new notes imported.
- 10,202 notes were used to update existing ones.
Then to delete the old notes that should no longer be in the deck, search for:
"deck:Ultimate Birds" -tag:UB::version-2024-01-27
and delete all of those.