This is something which for some reason I am only just noticing after an update installed yesterday. I have played/updated since June but perhaps for whatever reason it hadn't occurred.
Whenever my Sims are in a space which is more expansive i.e. more distance between decor objects or even just standing at the lot's edge arriving home from school/work, they are getting an "Undecorated" negative moodlet. I thought perhaps this was because I had some junk items in the corner of the lot from the debug menu but these don't actually have Environment stats so I seriously doubt it.
Seeing more online now and other people's experiences it seems to be a bigger problem owed to this change.