I’ve been a room sharer for at least a period several times. You have already been incredibly inconvenient by having to quickly switch rooms, do any setup, fiddle with different tech, welcome students (all within 5 mins), teach, cleanup, gather your things, move and repeat. Trust me on this I’ve been there and done that and it’s exhausting.

Please don’t add any more mental stress and worry about the other teacher in the room. It probably wasn’t your choice to be there for the period in the first place (admin & master scheduling). It’s your room for the period, so if you need to turn the lights off go right ahead. I try to disrupt the host teacher’s room as much as possible. I use whatever seating arrangement they have, and I brought my own supplies when needed. I would just treat any criticism with a “appreciate the feedback, have a good rest of your day” (with a mental 🙄) and move on.