Polyfats are unstable by definition, so when you cook with them, they go rancid pretty fast. That is all very well known.
Besides, seed oils usually produce imbalance of w-3 vs w-6 fatty acids which is also deemed to lead to pro-inflamation effects.
This is all very well known and not a hype. Here is a review from 20 years ago:
https://www.sciencedirect.com/science/article/abs/pii/S09523...