Originally Posted by kovidgoyal
IIRC when you merge a tag, all books that have the original tag, not the destination tag are modified.
That was what I expected. 1 book
something caused 700 others to change their modified date. That tag rename was the only thing I did at that time(stamp). The destination had a few hundred. That leaves the question why 500 more got touched. Maybe I am a klutz and more books were (unintentionally) selected than visible for some other operation
I will keep watching. maybe I will find what updates so many books