https://www.bleepingcomputer.com/news/microsoft/microsoft-re...
Microsoft's other software uses "microsoft-edge://" links which simply ignore the user's default browser choice and open in Edge. When a workaround was found to fix this (i.e. to obey the user's choice), Microsoft blocked it.
Plus Microsoft rushed out this Edge-link workaround patch to retail, while sitting on the default browser UI improvements until next year.