What if John's retcon powers are just a paradox? I think he got that power from future John which results into an infinite loop of his future self getting trapped and his past self gaining his powers.

I mean they ARE explicitly a Paradox, the Treasure was used to trap the Souls of the 4 Betas, and cast into the Furthest Ring, where John found it and gained the Retcon Power, which is the only reason they were able to access Caliborn’s Session, and as such, the only way they could get trapped into the Treasure in the first place. Yay for Retroactive Shenanigans.