Yep, looks like molt to me.
I went out this morning and have a tail-less rooster, he was looking pitiful
You can give a bit of extra protein - eggs, fish (tuna, mackerel, sardines, meat/beef) if you wish. I've done that in the past.
Some seem to have a harder time during molt than others and do go off feed a little too. I've found they are usually really keen on something green like Kale, Collards, Cabbage, etc. too. You give these things anyway, so I'd keep things relatively normal, but giving a few healthy "goodies" - they may like that.
I feed a 22% protein feed, so don't give lots of extra protein unless I'm just overrun with eggs, I feed those back at times. I sprout some lentils or oats, I need to get some more started, I've been slack, they LOVE sprouts. BUT, to be fair, they have had apples, grape hulls (from making juice and jelly!), tomatoes and cabbage from the garden, so they are not dying