it wasn't any of those. But now it's disappeared. I'm not sure why.Red saws he saw it in his Discover software window, and I'm not the one to argue that possibility, could be new?
In my Kubuntu, I had to actively search Discover for firmware, and got quite a number, I do not know if there is an answer there.
The updates shown in Discover Software are os updates, there are packages with "firmware" in the name that need updating, so if you don't see them anymore those packages have been updated. So what you were asking might have gotten confusing responses, what @atanere advised was how to update your bios/uefi firmware which is done by copying the most recent bios/ueffi firmware to a usb drive and then using that to flash you bios/uefi.it wasn't any of those. But now it's disappeared. I'm not sure why.
For the others, I've done firmware updates via usb stick a couple times with no problems, I was just thinking this was something new.
But like I said it's gone now. I don't know if it updated or what.