I reached out to Google Chat support, and took the following steps:
1) Plug the charging case into a power source using the included USB-A to
USB-C

cable. Ensure that your Pixel Buds are seated within the charging case and leave the
charging case open. At the back of the charging case, press and hold the pairing button for 30
seconds. When the earbuds status light stops blinking, let go of the pairing button. The earbuds
status light will blink white and orange until the reset is complete and then start blinking white to
indicate that the Pixel Buds are ready to be paired. Your Pixel Buds will be reset.
2) Clear the phone's Bluetooth cache (Settings>Apps and Notifications>See all
apps> menu bar>Show system apps> Bluetooth> Storage> Clear cache.
Now, after clearing the cache, I went ahead and reset the buds again to be sure. Now, I can leave In Ear Detection on, and when I cup my hand over an ear, there are no cut outs. I'll try out a phone call after work today and report back, but so far, so good!