[hunter2_]

Almost. The laptop of the person being interrupted is essentially muting its mic temporarily to avoid sending an echo of the interrupter. You could say it's prioritizing its speaker over its mic.

Basically, of all the ostensibly unmuted mics, only the one with the loudest human is truly unmuted.

It's closer to half-duplex than full-duplex. Full-duplex with no artifacts requires no echo cancellation which requires headphones.