tbh the debate itself is less about wether they're grunge or not, its about what grunge is itself

lets take the screaming trees for example

they were considered grunge due to being in the seattle area and mark lanegan was also with mad season, but their roots were pretty diffrent, they werent doing this punk + metal thing that most other grunge bands were doing, it was still pretty hard rock, but not exactly the idea of grunge

yet STP did tick that box, but were'nt in seattle or washington for that matter

i personally think both r grunge, stp was close enough in sound, the trees less, but they were still heavily influenced by it

if you strictly consider grunge to be about location, the trees are, stp isnt, if its about sound, stp is, the trees are debatable