When I upgraded my iPhone to iOS 8 (in 2014), it stopped connecting via bluetooth with my car (2011 Subaru, FWIW). Apple told me it was a Subaru problem. I reiterated that the problem was caused by my upgrading iOS, and that nothing changed in my car. They said to get a firmware upgrade for my car.
So incompatibility can be symmetric, but for people with an expectation based on prior compatibility, the party that whose update triggers the issue will be seen (fairly or not) as the cause.
E.g. if you sell an office suite and it doesn't support DOC and XLS files, it's your fault and users will call you for it. It's not Microsoft's job to go make sure Word and Excel work with your office suite.