Unless otherwise stated the versions supported are (Current - 1) or Current. So if the current version of Chrome is 88 we support both versions 88 and 87.
While the extensions might run without major issues in older browser versions, we do not actively test our extensions in them and generally do not fix bugs that may appear in them.
Only the most current version of the extensions are tested and updated to fix bugs or add features. Users of older versions that find a bug should upgrade to the latest released version to determine if the bug has already been fixed.