
Honestly, I highly doubt Ryan actually lost his powers
We're talking about the world's only natural super, and so far they haven't explored that storyline. It's practically confirmed that The Boys will have sequels (in the form of spin-offs).
We didn't see him try to use them afterward. He was the only one unharmed in Kimiko's explosion, and his biology is unique; there's no V in his blood because his powers are produced 100% naturally.
He could very well have lied so that Butcher and the others wouldn't see him as a threat, or his powers were simply temporarily dormant.
Eventually, his powers should reappear, similar to Spider-Man.
I'm sure we'll see him in a future spin-off.