There are good examples of the opposite too - such as Boethius, one of the critical links saving classical philosophy from oblivion on the outset of the dark ages:

https://en.wikipedia.org/wiki/Boethius#De_topicis_differenti...

Indeed, the Church is responsible for preserving many ancient pagan records that would otherwise have been lost with the fall of Rome. Islamic scholars also played a role in this (e.g., the surviving Aristotelian corpus).

Like what? And why would you suspect that? Christian apologists and scholars were active in debating pagans and drew from pagan philosophy, science, etc. And part of the job of an apologist is to respond to things which do not conform to what you cynically call the “party line”. So you should expect various records that reflect that. There’s ideas would resurface sooner or later.