Re: Gray treefrog tadpole tail problems
If it was me, I would give it more time before making a decision. I have seen that level of kink in the tail before. Gotta wait till the tail disappears to see what's up, maybe longer. If it makes you feel any better, he is in no distress due to difficulty in feeding because the majority of this energy is coming from the tail at this point, I believe.
On a different front, I again confess my ignorance of tree frogs, but when front legs pop in my dart frogs, I get them out of deep water. The only times I have seen kinked tails like in your pics are when I was late in getting the frogs out of the water (maybe he is absorbing the tail too fast due to energy consumed by having to tread water all the time? no idea). In darts, when the front legs pop, the gills are about gone and replaced with lungs. Darts will drown if left in deep water too long. I always move my guys to a tilted grow-out when the front legs emerge. Please check that with a different source to make sure that's true of your little guys, too, though.