One approach is proactive and the other reactive. Unless, one checks the release notes every 4 weeks... I would argue the utilitarian approach is exactly the other way. Verify and test if there is an API break with a major version change. Whether the browser is 2 years or 10 years old shouldn't make a difference.
Since there are more websites than extensions, the utilitarian approach would be to choose 2019-10 over 76.0.0.