Although the Pixel and Pixel XL are nearly two years old, there is a small consolation for shutterbugs that still own the handsets. When released, Google promised to offer unlimited original quality photo uploads to its Photos service for free. If you have been using it as is, carry on about your day. But if you have installed a custom ROM on your device that was based on AOSP (Android Open Source Project), you might want to check to see if your photos have been counting against your storage.
The problem is due to a typo that was found in AOSP that has since been corrected. The issue was first discovered by a senior member at XDA Developers sometime in January 2018 that saw the Google Camera app improperly tag photos with "google" instead of "Google". It's odd to think this problem would occur simply by using AOSP as a base, but apparently, in the build scripts for the Pixel and Pixel XL, it was set to "google" by default, which is used by developers on the XDA forums.
To be clear, this does not affect the stock ROMs running on the Pixel, Pixel 2, Pixel XL, and Pixel 2 XL. The reason being that Google most likely has a different build script that it uses for its software. XDA goes on to state that since this issue was discovered in January, many ROMs have already corrected this problem but if you are running an older version, you might want to update to the latest version available.
Source: XDA Developers