Cock ring of fire immunity: Very Rare. Makes area surrounding and including the wearer’s reproductive immune to fire damage. Prevents STIs and can be toggled to destroy sperm cells in ejaculate

Well yes, but actually no. BG3 crit fail and DMG crit fail are different

Crit fails like that are referenced as an optional rule in the DMG, minus the Nat 1 part

Yeah. Larian made some really good changes to D&D, then they added crit fails to skill checks