Yes, he should not be posting pictures of him cuddling his ex.
However, if you have got a scroll back seven years to a time when she wasn’t his ex, then it’s just a picture of him with his girlfriend. He’s allowed to have that. If you don’t like it don’t scroll.
Tell him. You can always break up later if it doesn’t work out. But if he’s with someone else you’ll have lost your chance.
Yes, he should not be posting pictures of him cuddling his ex.
However, if you have got a scroll back seven years to a time when she wasn’t his ex, then it’s just a picture of him with his girlfriend. He’s allowed to have that. If you don’t like it don’t scroll.