Safest Way to Clean Grass Juice Off FPV Cameras?

Probably just water and a microfiber cloth

I like to use camera lens cleaner, sprayed onto a q-tip and then rub the q-tip around lens in a circular pattern until clear

I'd say isopropyl, or would that chemically attack the lens somehow?

like otehrs have said, microfiber cloth. if its water inside the lens... thats a bit more different and probably need some Alch to get it off.