Mozilla on the coming version-100 apocalypse

Both Firefox and Chrome are racing toward releasing version 100 in the near
future, and developers for both browsers are worried
that web sites with naive code to parse the version number out of the
user-agent string will break.

Every strategy that adds complexity to the User-Agent string has a
strong impact on the ecosystem. Let’s work together to avoid yet
another quirky behavior. In Chrome and Firefox Nightly, you can
configure the browser to report the version as 100 right now and
report any issues you come across.