I mean, they’re fogging because the top of the mask leaks, and the breath takes the path of least resistance and goes around rather than out of the mask.
Likely, but not necessarily. My silicone half-face (with disabled check valves) slightly fogs my glasses because enough water vapor is leaving the filter close to my glasses. I'm sure it's not leaking, because I can feel the silicone pull away from my face when it does.
