Desktop apps and command line tools that provide OAuth links typically don't care which account you're signed into on Firefox when they provide an OAuth link, even if the app itself allows fast-switching between multiple user accounts. It would be more productive to specify which container should open for certain multi-user account platforms (such as Google or GitHub), or… even better, have the container selection dialog open automatically based on the detection of an OAuth link. This would ensure that the access token gets handed over to the correct account for authorization or integration.
Method 1
New Option "Always open this site in…" -> "Ask" [Good Option]
Method 2
Ask which container should open on detection of OAuth link (URL Matches on some combination of "oauth", "request", and/or "token) [Better Option]