thumbs.db still lives. Even in Windows 10, where you’d think by now they’d have ditched it.
If I set thumbs.db as an ignore pattern, it throws the folder immediately out of sync once ST is restarted. I want to see thumbnails in Explorer, so Windows helpfully creates the db file. If deleted it gets recreated.
As the thumb.db files are already in the global index, you need to do some extra steps to get rid of the out of sync.
I suggest you add the ignore on every node except one. The exception should be on a node, which has all thumb.db files. Then delete all the thumb.db files on that node and rescan. After that, restart all nodes and the thumb.db files should not make any problems anymore.