I don't know which interview you're talking about, but in any event you don't know what his motivation was for saying what he said when he said it. Perhaps he was wrong, perhaps he changed his mind, perhaps he was rationalizing on the fly, or perhaps he lied.

It's clear that what he and other scientists said about masks early in the pandemic certainly changed over time. I think science is like that. People who like simple, certain, unchanging answers can get them from religion or ideology. People who don't mind complexity, nuance, and change are more comfortable with science.

Assuming Fauci was lying because what he said then isn't what he is saying now just isn't logical.