Google has acknowledged the Bose Quiet Comfort 35 II Google Assistant bug which has been affecting some users of the headphones that were announced earlier this fall. According to some users over on the Google Product Forums the issue is that they haven't been able to use their headphones for Google Assistant functions, whether that function was asking a question or trying to initiate a request for Google to do something.
There are a few factors here worth mentioning if you were unaware of this problem in the first place. The first is that based on the Google response this isn't a problem that seems to be affecting Pixel phones, so if that's the case then it may just be other devices which are attempting to use Google Assistant through those headphones and Pixel phone owners should be ok. Another important factor is that this is said to be with devices that are running on Android Oreo only, so if you have an older non-Pixel device and aren't on Oreo, but you do have these headphones, you should be ok as well and not experiencing the same problem. Lastly, Google says that it's aware of the issue affecting Pixel Buds users too so it's apparently not just owners of the new Google Assistant-powered Bose headphones that fit over the ear.
Naturally, one might think that headphones with Google Assistant integrated into them would work best with Google's devices, but just because one owns a non-Google device that shouldn't mean the phone isn't capable of using a feature through a pair of Bluetooth headphones that is already installed on their device and is completely functional without the headphones connected. Google knows this which is why it's looking into the problem. According to some users the issue has been popping up on phones like the OnePlus 3T and the Sony Xperia XZ1, though it's possible that more phone types are included. For the time being Google hasn't mentioned a date for when a fix could be expected so it might be a little while before a fix is implemented and pushed out those having the problem. The good news is that at least Google knows about the problem and is working to get it fixed up, saying that it hopes to have the fix in place for the next version of the Google app, whenever that happens to be released.