Now that [https://github.com/jellyfin/jellyfin-web/issues/5626] appears to have been fixed, JMP probably should probably be rebuilt to include 10.9.4 so that users are able to login after token is somehow invalidated.
The "Force External Web Client" option also fixes the problem for users that updated server to 10.9.4. However, I suspect most users would not know about that option -- I just discovered it myself.
Now that [https://github.com/jellyfin/jellyfin-web/issues/5626] appears to have been fixed, JMP probably should probably be rebuilt to include 10.9.4 so that users are able to login after token is somehow invalidated.
The "Force External Web Client" option also fixes the problem for users that updated server to 10.9.4. However, I suspect most users would not know about that option -- I just discovered it myself.