I received the following Audit Issue in Chrome 95's developer tools today:

A page or script is accessing at least one of navigator.userAgent, navigator.appVersion, and navigator.platform. Starting in Chrome 101, the amount of information available in the User Agent string will be reduced.

To fix this issue, replace the usage of navigator.userAgent, navigator.appVersion, and navigator.platform with feature detection, progressive enhancement, or migrate to navigator.userAgentData.

For more information, see:
https://blog.chromium.org/2021/09/user-agent-reduction-origin-trial-and-dates.html

The script it is referring to is:
/lib/babel-polyfill/polyfill.min.js in in Moodle 3.8 to 3.11
/lib/polyfill/polyfill.js in Moodle 4.0+

Note: Current version of Chrome is 95 so you have a bit of time to address this.