Strange marks on kitchen ceiling

Hi, I have noticed some strange marks on the kitchen ceiling. They are next to the front door. Above them pretty much directly is a joist that runs long them. My initial thoughts was the shower above was leaking, buts it dry and no signs of wet marks under it ( its raised above the floor so easy to see ). I then had a feel under the floorboards from the room above and cant feel anything wet either. Anyone got any idea of what they could be?

Thanks

Could be condensation stain in a kitchen especially if you don’t have an extract fan in use .

I would go with water stains- meaning that you have, or had a leak. I wouldn't lose any sleep unless it gets worse. I recommend that my customers use a pencil to trace the outline and see if it becomes bigger. BTW, I am decorator rather than a plumber.

I think it is unlikely to be a condensation stain- I am willing to bet that the stain is at a joint in the plasterboard.

My mum recently had very visible water stains on her lounge/kithcen ceiling. I started cutting holes. I then realised that it was a double skin ceiling and that the water stains were travelling 3m away from the source (an exterior window).