You've got a lot going on here that is not good. Wrinkled skin is a sign of dehydration, though I'm sure he's lost weight too you need to get fluids in him ASAP, unflavored Pedialyte is best at this point. As said above you can mix the Pedialyte with some squash and chicken or squash and turkey baby food and get an eye dropper or very small syringe without the needle. You can try to get it in his mouth but typically you'll have to drop it on top of his snout and let it run down over his mouth, then as he licks it off put more on top to run off, etc. Get as much in him as you can.
His diet is not good at all. The crickets are good, he should eat at least 25-30 a day of medium sized at the least. But never feed freeze-dried veggies or fruits, that's pointless and one of the reasons he is so dehydrated. Beardies don't drink much straight water, they get it from FRESH VEGGIES AND FRUITS. Freeze-dried veggies and fruits have zero water in them, and crickets have very little. I'd go and buy some wax worms at Petco or PetSmart, you can buy 50 for $4 at Petco. They are fattening and full of liquid. Normally they are only a treat but he's lost weight, is very dehydrated, and needs energy. Usually they go nuts over them, give him as many as he'll eat, and follow with the unflavored Pedialyte/baby food slurry.
Do not give him kale, it's not good for them as it leaches calcium out of their system (it's a weird veggie). You need to be dusting his insects in powdered calcium with D3 and sprinkling it on all of his veggies EVERY SINGLE DAY UNTIL HES OVER A YEAR OLD! And he should get a multivitamin and mineral powdered supplement 3 times a week with it. Your UVB tube bulb needs replacing, and the Exo Terra one sucks, it is not close to the right wavelength of UVB for a beardie. So the bad UVB tube plus bad veggies plus dehydration plus not nearly enough calcium and multivitamin is killing him.
You need to get a Reptisun 10.0 T8 UVB Tube bulb and put it in your current fixture, it will fit if you get the same length. Now this will do no good at all unless he can get within 6 inches of it. And it should be hung inside his tank, not on top of mesh or glass as this absorbs more than 50% of the UVB. But go get the Reptisun now, it's very important. And do not ever feed him freeze-dried veggies or fruits again! No kale! The best veggies for him are collard greens, mustard greens, endive, escarole, squashes, sweet potatoes, peas, broccoli, green beans, etc. I add a small bit of apple, strawberry, Mango, papaya, bananas, grapes. Not too many fruits though, too much sugar. But it provides lots of water. Walmart sells a big bag of "Mixed Country Greens" for under $3. It's huge and it has collards, mustards, a bunch of good stuff. It's on the top shelf above the fresh collards and mustards, and next to a big bag of kale. I also buy their little bags of different fresh veggies that are in the same section for $2.98 per bag.
So please make these changes immediately and stop the freeze-dried veggies! I'd like a photo to see how bad he is, but I can tell he's starting to regress because of the lack of proper and strong enough
UVB light and no calcium absorption or processing. The
UVB light effects every part of them, and if they go months and months with the wrong wavelength of UVB, not being close enough to it and having it obstructed by the lid, and then not eating any calcium from proper veggies and fruits and not getting powder every day, this is all compounding and he's sick.