DM physically altering characters, without any prior discussion

Hey, just wanted to hear other people's opinions on a recent situation.

for context, i have been playing for a while, but mostly stuck as DM for a couple years now. finally found a group that i could be a player at, and we are running through a dungeon, and this DM has these creatures/encounters where the creatures will steal teeth straight from a PC's mouth on a failed con save. when i brought it up to the DM that it made me uncomfortable he was altering characters without a warning or session 0 discussion, he brushed it off, and has continued to do so. there was even a comment about bigger things later in the campaign.

now in all the stuff i've run, and groups i've been in, i've never ever seen anything that would alter someone's pc permanently, and any change made to someone's character, has been either discussed or the choice of the player, for example: a player of mine got hit with a lightning bolt and wanted a scar from that interaction (cool).

i'm open minded to these changes, but feel like there should have been a conversation first, but i could be wrong so i guess the question i want peoples opinions on is:

is it okay to change other peoples pc's permanently, with out prior discussion?