the phrase “about it using” is a shortened form of “about its use of” and should never be replaced with (the completely broken) “about it use”.
EG1: “This confirmed her suspicion about it using an illegal substance.”
EG2: “About it using a red cape: I think it’s meant to make the blood harder to see.”
EG3 “this confirmed their fear about it using tap water, instead of the mandated laboratory grade purified water.”