Popped a tire the other day and had to throw on the full size spare (Volvo s60 AWD)

Tire looked low, but I had to bite the bullet and drive on it. It was at 15psi. 25 miles later, I’m able to get to a pump and bring it back up to 34psi. I’m getting my OG tire patched later, but curious if the spare is salvageable. It’s clear that tire was riding a bit on the sidewall, but was not completely flat. I’ve seen sidewall interiors get ripped up from riding low, but not sure at what threshold that would happen at. Any input is welcome. Exterior sidewall is scuffed, but not damaged, gouged, or worn.