Here are the details:
The text reads, for anybody Googling:
Device Firmware Unifying Receiver (RQR12)I vaguely remembered reading something about how a Gnome upgrade was going to allow Gnome to update firmware for connected hardware, and indeed this is the explanation for the notification I saw: the USB dongle for my mouse (and other Logitech hardware) needed a firmware update, or a hacker sitting under my table might have been able to interfere with my button presses with my wireless mouse.
Device Update RQR12.01_B0019 > RQR12.10_B0032
...This release addresses an encrypted keystroke injection.
This was confirmed by the excellent arch Linux wiki:
A quick check with Synaptic (running in non-admin mode, of course, because Buster uses Wayland), revealed that the fwupd daemon was indeed installed.
So there you go: Gnome now offers updates to firmware for connected hardware.
If you are the one person running Gnome who comes across a similar notification, is curious, Googles it and arrives here, I hope you find this post helpful.