I bought a Canon PIXMA MX895 all-in-one printer in May 2012. In fact, I was one of the first owners of the printer in the UK, having pre-ordered it the previous month. The printer was on sale from then until around April 2013.
One of the features the printer had was Google Cloud Print. The printer didn't support it out of the box – it needed a firmware update to add support for it (although it was available on day one). And, since then, I used the Cloud Print feature sporadically.
Fast-forward to late last year. I tried to use Google Cloud Print, but all I got was useless error messages from the printer about it not being able to connect to the server. Suspecting something was up, I set about Googling and can came across this discussion. As it transpired. Google deprecated the authentication API the device was using in April 2012, before there was even any stock of the printer in the UK. And, while Canon have released firmware updates for more recent models, for some models Canon will not release updated firmware, stating in a support article dated 1 September 2015:
Google has recently announced future planned changes to the server authentication method of their Google Cloud Print™ (GCP) service. An impact of these changes will be that specific Canon printers will no longer be able to support Google Cloud Print™ (GCP) because the printer firmware cannot accommodate these planned changes.
Recently is certainly a stretch. I suspect what they mean is that Google recently followed through on something announced over three years ago. For models other than my one, the timeline is even worse. The MG5450, for example, was announced in September 2012 and on sale until around September 2013.
Needless to say, I wasn't exactly impressed on learning all of this. To top it all of, as of writing, Google UK are still listing the MX895 as a Cloud Print printer1.
1No idea if that link will redirect outside of the UK.