Pixel 3 bugs have been taking up far too much of our time recently, but thankfully this is one that is very easy to fix. Some users have been noticing that while recording video, their Pixel 3 will still vibrate for incoming notifications, causing the video to distort along with the buzz. This is something that should be prevented by default, and the solution is simple.
On most Pixels, including the 3 XL I have in front of me, the camera is one of a number of apps that is given access to Do Not Disturb settings outside of your control. This means the camera app is able to dictate certain situations in which it can enable DND features without you even knowing. So when you're trying to take a photo or a video, no sound or vibration is allowed, which makes perfect sense. If that's not the case with your Pixel 3 or 3 XL, it's because for some reason it doesn't have the correct access by default.
This is fine < - > This is not.
To fix it, you need to search "Do not disturb access" in settings — it's not with the other DND settings but rather under Apps & notifications > Advanced > Special app access. You'll now see a list of apps with toggles, and you simply have to make sure Camera is toggled on. This grants the camera access to set its own DND rules which will, in turn, stop any annoying vibrations during video recording.
Why some Pixels are shipping with this toggled off, including Artem's, is anybody's guess. But at least it's not difficult to fix.