Many people, like myself, look at Google's phones for one specific reason: they have an easily unlocked bootloader. That means when software support runs dry, or you get the itch to root/ROM, you can modify things without having to compound any potential security concerns with additional issues like exploits or undocumented software. If that's your motivation too, this news could be a small concern. Some Pixel 2s purchased directly from Google seem to have locked-down bootloaders. 

If last year's Pixels are anything to go by, typically it's just the Verizon models that have locked bootloaders, lending some credence to the theory going around that Google may have inadvertently shipped some Verizon models in place of its own unlocked SKU, though hardware IDs don't seem to agree. A how-to unlocking thread on XDA Forums has a good number of reports for the problem, and a thread on the issue tracker has been started.

This issue seems to only affect the smaller Pixel 2, not the larger Pixel 2 XL, and it manifests as you can see just above, with the developer option to unlock the bootloader ("OEM unlocking") disabled. As yet, there appears to be no recourse short of device replacement.

Bootloader unlocking is a somewhat niche topic, so most of those who might be affected will likely never know. According to a comment posted in the issue tracker, Google is currently investigating the issue, so if we hear more, we'll let you know.

Thanks: Elbert, Richard, Ed, and everyone who sent this in.

UPDATE: 2017/11/21 2:40pm PST BY

It's fixed

Google says the issue is fixed and advises a factory reset.

Source: Google Issue Tracker, XDA Forums