Can't More Firefox Tabs Over Discord

This is just a small bug that I noticed and it's really only noticeable if you have two monitors.  Typically, if you pull a tab away from your browser and move it to the other screen, it'll instantly change into a new browser window.  This process is a little different between Chromium Browsers (Chrome, Edge) and Firefox.  Specifically, if you try to pull a firefox tab over to make a new window, but already there is the software version of discord, the new window doesn't appear.  Again, this only occurs if you try to make a firefox window from a tab and Discord is already open and you try to pull the tab over it.

Not a major issue, just a minor annoyance.  I'm just curious about this.