I once had a young guppy jump out of the tank and couldn’t manage to get him to stay still to scoop him up so had to end up using my fingers to pluck I’m up and toss him back in. The poor thing ended up very crooked and definitely had a spinal injury even though I was as careful as I could be but it lived as long as the others did. I considered putting it down over and over because it seemed horrendous and painful to even look at but once it was back in the water it never acted off or anything so I let it be. (This was years ago, I had a lid on the tank but took it off for maintenance and walked away like a dummy). I also had a betta jump with a lid on the tank and also had a bit of a crook but he lived for another 3 years and never seemed bothered by it other than the initial shock of the impact. Definitely could be what happened to your guy here if you have a lid on the tank. Better than jumping out tho!!