Shot this one few minutes back and a google lens search told me that this typical appearance of clouds is called a 'mackerel sky' since it resembles the skin of a mackerel, which I've never seen or touched in person. I guessed it was called such because the clouds look like a school of fish.
It's also called the 'buttermilk sky' because of the curdled sort of appearance.
A BBC weather post which features some beautiful images called it the 'fleece-covered' sky which is a great name in my opinion.