Based on reports from both the Google Support Forums and on Reddit, the issue is persisting in much the same way for all users that are experiencing it. Which is that audio will just cut out for a couple of seconds randomly.
The problem also reportedly happens more outside. Though users have experienced it inside as well. It's also worth noting that this isn't an issue that everyone is having. Though it is more than a handful of users, it's not widespread enough that it's impacting everyone that has a pair.
Pixel Buds audio is cutting out on brand-new pairs
For some this is happening to the Pixel Buds as soon as they open the box and try them out, with one user on Reddit stating that they noticed the audio issues immediately on a brand-new pair.
Other users report that it appears to be happening more often based on various factors. Such as where their phone is placed when on their person, like a back pocket.
Google has already sent out some firmware updates to the earbuds, but it doesn't seem like that has fixed anything. Users were still reporting the issue even after the most recent updates. Ranging from firmware version 225 all the way to 295. Which is the most recent.
Contacting Google Support might be in your best interest
If the issue is happening often, and it bothers you, it might be in your best interest to contact Google Support and see what they can do for you.
Other than speaking to them about a possible refund or exchange for a different pair, which some users on Reddit have suggested to those having the issue, your only other recourse is waiting it out to see if Google can fix it with software updates.
The thing is that, if the firmware updates that have gone out already didn't fix the issue, they may never fix the issue. It's also possible that it can be something fixed by software but Google just needs to figure out the main cause first.
Since it's also not happening to everyone, getting an entirely different pair might be a good option. That is if you're within the return period and Google will allow it.
If the audio cutouts don't bother you much, then hopefully Google will eventually send out a fix.