Which package(s) provide this? I have one installation where they are missing. Clearing caches didn't help. Which file(s) in ~/.trinity/share/config/ can be deleted to affect only window decorations and whatever else might be causing this?

I sent this to the users list more than 60 hours ago and got zero responses so far. At the time it was in 15.2. This time I upgraded a freshly updated 15.2, then cloned it and upgraded the clone to 15.3 (keeping the 15.2 TDE repos), after which this occurred. I have others with both 15.2 and 15.3-using-15.2's-14.0.9 that are behaving as expected.