Google plans to freeze the User-Agent and switch to Client Hints for web sites to identify information about their visitors. User-agent strings have become convoluted and unwieldy and are a privacy risk as Google states they are commonly used by fingerprinter scripts to track users. Google hopes to remove bugs as part of this plan to remove access to legacy servers as well as to avoid bugs. Google says this plan will reduce the complexity of updating User-Agents and reduce the privacy of its users.
Source: https://www.bleepingcomputer.com/news/google/google-chrome-aims-to-make-browser-user-agents-obsolete/