Over-watered seedlings?

They are going to die off and drop off soon enough anyways so dont worry about em. You can see the soil is still quite damp, so its likely the roots are not getting as much oxygen as they need, So unless u want to start poking pin holes in the cup to allow more air in, all you can do is wait for the soil to dry out on its own over the next few days and the plant will start growing when the oxygen levels around the roots go back up. The more perlite I seem to add to my seedling mix the better they seem to do, im up to about 50% perlite and 50% fine potting soil these days. U can also sorta gently squeeze the cup sides lightly to break up the soil a bit and allow some air in, but do it gently so u get small cracks in the soil surface, air doesnt need much space and u dont want to damage the roots, so softly is enough. And yeah, its what i do for mine when I over water em and the soil compacts a bit like that. Thats why i use more perlite in the mix now for their first container.