Hair chewing

Got to get to the root cause. Sensory seeking? Anxious? Stimulating the jaw (does she snore/mouth breathe?)?

My 5 year old has just started this so it would be interesting to see xx

It's a self soothing behaviour or they do when bored.

See when she does it. And is there something else you can give her to occupy her hands or to soothe?

If it's not stopped it can potentially lead to Trichotillomania which cannot be cured only managed and is a lifelong struggle.
Watch for signs of hair pulling.
Don't try and tell your child to stop the chewing as they will just do it more.

Instead, when you see she does it, just gently pull her hand away or the hair away again and again and again and again.
She might also do it subconsciously so don't realise she is doing it, just divert the behaviour.

Or you might have to cut her hair shorter.

But again, watch for signs of hair pulling.

No advice but I know how frustrating it is I have a nail biting issue.

I bite my nails when anxious or watching telly etc.

I can’t stop myself no matter what I’ve tried. I’m embarrassed by it but I cant stop.