It's hard to tell from the pictures-are they the older, lower fronds? How does the new growth look? I'm no expert, but it looks like maybe sunburn to me? Are they all up against the block wall? Is the wall south facing?

Also if you did overwater and create root problems, which is possible, you can water them a few times with 1 part hydrogen peroxide(3%) to three parts water. That’ll help kill off some fungal or bacterial issues while adding additional oxygen to the roots. Keep us updated

Looks like planting shock and sun damage. My queen palms were put directly into the sun, they looked like this right after as they were put into the September blazing afternoon sun. This damage cannot be fixed and will not go away until the frond dies. My queens still have this damage, but i have cut the leaf tips to make it look better. Consistant watering is a good help to get it out of shock while it gets established.

I don't know if they are for full sun in the desert. Some shade is needed for hottest parts of the day. i'm sure in dappled light they do great...with plenty of water. Most palms like plenty of water in Phoenix. Date palms grow next to rivers in Africa..so even they need help.