Hi Robert and welcome to Goy. Looks like wind scorch to me Jap. Acers hate strong winds with a vengeance and their leaves shrivel up and die. You've also got the pot sat on a concrete slab so it can't drain so it could also be too much water. In addition to that you have it against a fence in what appears to be full sunlight. Jap. Acers need semi shade, protection from wind and can't sit with their roots in water. Either plant in the ground or move and raise the pot up on bricks or stones. Be aware that growing in a pot it is going to need constant attention and watering, much better off in the ground!

I hope it recovers but its asking a lot. I learned the hard way about shade and shelter so you have my sympathy.

Thank you all.

You could try it in John Innes No 3 compost with a little ericaceous compost mixed in the top, if not already done so, most like moist soil on the acidic side I believe, that is where mine are and fairly sheltered, as stated above, hope you can save it :-)