When I'm talking about "gain-of-function" it means Fauci and co. DELIBERATELY did so to weaponize it. For exactly what purpose, well that's debatable.
Taking a virus known to infect humans and exchanging its spike protein with a spike protein from a bat virus is not, in fact, “gain-of-function” research. It is research intended to determine if the bat virus can attach to human cells without actually using the bat virus. If a bat virus can attach to human cells, it might be able to cause an infection in humans. If it cannot attach, then it cannot cause infection.
I notice that most of those who are yelling about “gain-of-function” actually have no idea how molecular biology research is done, nor do they have a clue what “gain-of-function” actually is.
Ever see those green, yellow, pink, etc., zebrafish at a pet store? Those fish have been subjected to gain-of-function genetic alteration. They don’t naturally come in all of those colors, but someone inserted genes that cause them to produce color pigments they don’t naturally make.
Exchanging homologous proteins from one species to another is a common research technique.
So theoretically mad scientists can make humans in a rainbow of colors.