I doubt it changed for normal soft attributes. It has to do with items
being iterated. If you search the blaster on my previous posts, I discussed
the fix in 9.1 and earlier systems via SQL a couple years back.
I'd have to recreate your situation to confirm it changed, but if you did
remove all visible uses of it, it is likely the hidden implicit row stored
that is still not removed as part of protecting the iteration of the type
identifier.
If you cannot find the posting, I can verify if it is still relevant and
repost.