We had this bug:
https://github.com/discourse/discourse/commit/3d0ccf864243fdfecc07ad3764df499a7b7a55f8
And I improved the implementation with this feature:
https://github.com/discourse/discourse/commit/3877ef2cfa17155a4c6063d6d3625c9bd4d5b5df
We had an edge case where when a user liked a post by another user and then followed up by editing it we would not notify on the edit.
Additionally I added a safety guard that ensures we notify unconditionally once a day even if it is a repeat editor. (we suppress repeat edit notifications from the same editor for 1 day). This is not configurable at the moment.