My thinking too. Have no idea what injury he supposedly has / had, but hope he at least manages to get to a place where he is training regularly with the first team again.Not one to speculate on players personal lives, but it wouldn't surprise me at all if there was a mental issue there. Or a personal thing we don't know about. His body shouldn't be this broken down at his age.
Players only miss an entire season if they fracture a large bone (oi oi) or something like that. Nobody even knows what Jones' injury is that's kept him out nearly 2 years.
Like you, I don't want to speculate, but if he is having issues with mental health then we as a fanbase may feel a tad bad when we use photos of him like that in this thread to mock him, even in a jokey way.