May be OS-specific, or it may not happen when you've set Firefox to restore previous tabs when restarting, or there may be a way to turn it off.
I don't remember seeing many of these on my actual machine (I did get the color scheme nonsense if I remember correctly), but I'm constantly seeing these in dev/testing VMs where I just installed it for testing and occasionally keep it updated.
I don't remember seeing many of these on my actual machine (I did get the color scheme nonsense if I remember correctly), but I'm constantly seeing these in dev/testing VMs where I just installed it for testing and occasionally keep it updated.