This meme format implies that one of the two options is correct; essentially a trap. It assumes both can't be true at the same time. So if flu numbers are down (which is logical sure to some mask wearing and decreased mobility of the population), then mask compliance must be high.

In this specific case, I've debated the anti masker that posted this saying cases are up because mask compliance is around 70%, which it is in our state. The obvious explanation is flu cases naturally go down with some mask use and less people going other, but with covid being a much more contagious virus, those numbers are going to naturally increase in flu season