It looks fine to me. It has lots of space still.

Has it got plenty of drainage and some semi shade?

Do vine weevils eat Hosta roots? It reminds me of an Aspidistra I used to have that was being chewed on by chafer grubs.

they can do especially in a peat based compost. Was it recently repotted?

Yes I did repot it a few weeks ago, I'll check for grubs, many thanks

If you have only just done it it could be due to root disturbance. I tend to do mine just as the new growth is just poking through 1-2cm out of the soil.