UV rays don't care about clouds or glass

Yes. Both.

Through a window, you’re mostly safe from UVB rays (the ones that cause immediate burning), because standard glass blocks them. But UVA rays — the ones that age your skin and contribute to long-term damage — pass right through. Sit in a sunny window long enough and you can definitely get burned, especially if it’s a car window or non-tinted glass.

On a cloudy day, up to 80% of UV radiation still reaches the ground. Thin clouds block almost nothing. Thick clouds might cut some UVB, but UVA sails through like it’s not even there. That’s why people get surprise burns on overcast days — they think they’re safe and stay out hours longer than they should.

Your skin doesn’t take a day off just because the sun is hiding.