The term “gain of function” is used by different people in different ways. It is a broad category of research and the misguided attempts to categorize it as dangerous in one broad stroke are not helpful. To quote Dr. Fauci:

"If all gain-of-function stops, you will have no vaccines for flu. You will have no vaccines for any of the other diseases, because all of that manipulates a virus or a pathogen to gain a certain function to be able to make a vaccine."