Just after the update to my Pixel XL i got a txt from my provider stating that i have just registered a new phone?. Additionally i had to set up my mobile banking app again (which involves a trip into town to use a cash machine affiliated with my bank as it is the only type that will register the app)
Zero warning form Google that this may happen beforehand, they are too busy toting PIP and various other completely useless things.
As an aside i haven't seen any battery life degradation or additional data charges, however i do live my life moving from one hot spot to another.
The most important thing to think about regarding the new Google devices, is how long the screen will last before it burns in the software navigation and home buttons. (I'm currently on my third Pixel XL in 9 months) Google will replace the unit completely but its simply not good enough for a flagship device.
No doubt i will be on my 5th or 6th or even 10th device by the time i get to the end of my contract, however i have been speaking to the ombudsman who believes I am entitled to a full refund after this many submissions using the argument that the unit is not fit for purpose.
Going back to the update, at least it will be rectified quicky. Google appear to be very good at fixing their software errors swiftly.