My guess was going to be Google Meets because I suspect this happens in order to pipe audio to their voice to text translation engine they use to offer you the live closed-captioning feature.

As well as, I assume, to archive a text indexable/searchable log of your conversations. I say this latter part based on multiple experiences I've had receiving clearly targeted advertising for topics I make random passing jokes or commentary about in live conversation, but which I've never once searched, click-imprinted, etc. for online. But, this is purely suspicious speculation. The live closed-captioning feature is a real thing and a thing I could absolutely see resulting in Google always sending audio streams to their backend for.