I don’t have the necessary expertise to evaluate the preprint. But here’s a response by BU about what they consider to be a mischaracterization of the research.

https://www.bu.edu/articles/2022/neidl-researchers-refute-uk...

So the 80% number is likely some kind of hyperbole that doesn't reflect impact on humans, but how can they claim this isn't gain of function? Gain of function is not only in the vector of virulence, it can be in any biological direction.

preprint: https://www.biorxiv.org/content/10.1101/2022.10.13.512134v1....