Launcher claiming that I have "already joined the game as a user" and will not open

Note: As the “Affects version” field would not allow me to enter the current launcher version (3.41.29), I’ve had to put this under 3.41.18 instead, as it is the most recent selectable launcher version.

When I attempt to open an unmodified installation of Minecraft Java Edition, the launcher claims that I have “already joined the game as a user” (see the attached screenshot) despite that not being the case, and, when I select the “start anyway” button, the Launcher appears to begin loading the game before closing (as normal) and nothing happening past that, instead of starting the game. Changing accounts, restarting my computer, and attempting to use the Quick Play feature all have had no effect.

I have had a friend of mine attempt to reproduce the issue, and they cannot.

Expected result: pressing the Play button on the launcher will open Minecraft

Actual result: The launcher acts as if it will open Minecraft, and then does not do so.