I have never, ever been burnt through clothes. I’ve seen people with horrific, near puce colour of sunburn that stops dead where the skin is milk white, protected by a t-shirt.
I am a Soldier in the middle east. Despite wearing a uniform, and under that a tshirt, I still tan. My hands, exposed to the sun all day, are not that dramatically different from my stomach, which is under 2 layers of clothing.
It is indeed possible to get UV through clothing.
Then again, the UV index out here daily is 9, and its 124 degrees out. There’s no cloud cover, and no shade…