Does anyone know what is causing this?

[FeatheryFlorence]

It’s like the paint has blistered on the wall next to the window. I don’t think it’s damp. Where you touch the blistered area it feels chalky and leaves a residue on your hands. It’s long overdue for repainting.

You have a leak somewhere. If the paint is flaking the wall will be damp somewhere.

I agree. That’s what it looks like at my work and they have damp

Roof, windows or chimney. If none of those an internal pipe.

Not aware of any internal pipes near there. Will check outside as I guess it might be the gutter.

Thank you all for your help!