I have two UNO boards from a few years ago. They look the same as far as chip placement goes.
I can plug both in and get flashing lights on them, and when I hit the reset (2x the on-off) button, they both make the same LED "noises". Since the LEDs on the non-detected board flash the same start-up sequence as a board that is detected, I assume both boards are working.
One of them has "UNO" printed on the circuit board and the other has "GCRduino Rev 1.0" printed on the circuit board. (edited according the comments for clarification)
I'm using Linux Mint 21 and Arduino IDE 2.0.3.
On hardinfo (the linux program), both of them are listed in Devices->USB Devices as "QinHeng Electronics CH340 serial converter."
The one that has UNO printed on the board is detected and I can load software onto it. The one that say GCRduino is not detected by the IDE and no new entry shows up in /dev.
The GCRduino is detected for a split second and then disappears again. check this video: http://100wires.com/arduino.mp4