I'm personally not very happy about this change. For some personal sites, I advocate for a no-JS approach, and the user-agent strings are the only way for me to understand the operating systems my audience is using. I fear that by making UA strings useless, JavaScript tracking just becomes even more indispensable.

EDIT: Apparently requesting more info from UA strings is still possible, but it's a multi-phase, stateful approach. See https://wicg.github.io/ua-client-hints/