I haven't been able to confirm this, but I swear it happens to my mom on Zoom. When I video chat my family on Zoom and she isn't sitting directly in front of the laptop, her words rarely come through. I can see her lips moving, I can hear my dad grunting in agreement next to her--but she's silent. If they switch places, I can hear my dad without issue.

I don't know if it's a combination of her cheap hardware or what, but it's... odd.

EDIT: grammar