Last time I disabled an ad blocker to try it on desktop, I was getting scammy looking product ads. On my phone if I browse Shorts (revanced doesn't stop those ads) it's all straight-up financial/health benefits scams.
But the other night I accidentally opened the 1st party YouTube app on my TV instead of Smart Tube Next and the ads were for big brands. So there's probably a different level of desirability based on content type and device type at play.
Using the permission to record audio triggers an on-screen indicator that the mic is recording. Someone would probably notice it on 24/7 recording. Someone would have also by now found the constant stream of network traffic to send the audio to be analyzed, because they also aren't doing that on-device.