Pics are too blurry to tell for sure, but might just be the periople(like the 'quick' of the nail), due to it being so wet. You'll need to post better pics to be sure.

 

Ok thanks I'll take better pics tomorrow

 

Sure looks like the periople, "cuticle" of the nail is shedding, lifting off from the wet conditions.
Some horses it seems to be a longer "cuticle" than on others is what I've seen on my own horses...
Better pictures will help...and loosie sharing helpful advice is great and a comfort to know from a professional viewpoint.
Don't pull it as it protects the hoof wall and is where the hoof growth begins..
If its got to go, see how to approach that that you can do and not injure the soft tissues underneath.
loosie will have some ideas I'm sure once she views better pictures.
🐴...

 

Looks like periople to me, too. I would gently trim off any hanging pieces -- without pulling on them -- and otherwise leave them alone. It's normal for them to peel and shed to some extent, but the same moisture level that's making them look white is also affecting how they're shedding. Think of the loose bits like a hangnail on your own fingertip. You don't want to rip them off, but you don't want to leave them hanging in flaps, either.