Of course legally they’re entitled to not do that, but google are also legally entitled to close your account for any reason they see fit. If they mass deactivated accounts on one of those clauses they’d likely legally be right but they’d be pulling a real asshole move, which is what affinity/canva have done here.
Surely if you want to oblige companies to release new versions because you purchased a version in the past, then you also have to oblige every customer to also purchase the new version. Which would be preposterous.
When you purchase something you should get exactly what you purchased, nothing more and nothing less. That's how business has been conducted for three hundred thousand years by now.
Affinity cannot deactivate the software you have purchased, that would be outside of the law.
No it is not and has never been. Of course not, and you must understand that.