I assume Microsoft Teams dropped support for older versions of Edge (e.g. these with a version number below 20). Only newer Edge browsers are supported - and there they dropped the last "e" in "Edge", so the user agent actually is "Edg/79.0". This was the reason why i made the user agent configurable in the current version 1.1 of this addon, in case there will be some other weird spontaneous changes in Microsoft Teams.