One of my bathroom walls is an external Victorian wall. It’s been damp checked etc. It was previously painted with matt emulsion with no problems, however I got same colour in Dulux bathroom paint and painted it in that, in August.
It looked absolutely fine, until about 2 weeks ago, at the same time it seems the weather got substantially colder (might be irrelevant).
Now it appears patchy all over! (The image is sideways for some reason)