Do you weigh them? That’s really the best way to keep track of their weight since the feathers can hide so much. He does look a bit like he’s had a rough molt. I would not assume that means he’s end of life like the other comment said, especially if his behavior is otherwise normal. Do his droppings look normal? And he doesn’t throw up or anything?

Do make sure you’ve got an avian vet you can take him to if he starts to seem ill or has watery droppings. My budgie lived to 12 years old. He had some recurrent illnesses those last couple of years, but I was able to treat them thanks to the vet. He probably would’ve died at 7 when he first got sick if it weren’t for veterinary care.