It’s expected in Discourse’s development – at least if you’re familiar with Discourse operational approach.
The design choice is to be optimized for the latest technologies without being stuck in extensive support for “old” software (I agree that “old” in this context is not exactly “old” and like many I don’t like to be forced to acquire new devices every X years 
), and there have been many similar announcements and discussions in the past. For example:
- Discourse is ending support for Internet Explorer 11 (IE11) on June 1, 2020
- Maintaining support for iOS 12 - 14 until January 2023
- Backwards compatibility with older browsers
- Why does Discourse prevent users to login with Safari 14.8?
- We're upgrading our icons to Font Awesome 6! - #43 by awesomerobot (not ios/browser related, but same logic applies)