Its probably not supposed to be supported, but when a user accidentally opens two Fibery Desktop instances, then some weird visual glitches happen.
The color-mode reverts to Light mode, and it just feels buggy. This is happening on both my Laptop and Desktop, so I imagine its a global rather than local issue.
It might be good to check whether another Fibery Desktop instance is already running, and just provide a warning/error to close the duplicate instance and use the original.