Summary: The numeric keypad part of my keyboard does not work correctly on my remote PC. The keyboard physically attached to the remote/host PC works normally, and while they are not identical, they are essentially the same classic 104-key US layout.
Symptoms: Main QWERTY keyboard part works normally. Entering numbers from the keypad, though, will return wrong characters (letters like B for 2, D for 4, E for 5, C for 6) or functions (0 will paste if I have text in the clipboard). This is what makes me think it's just mapped to the wrong keyboard, but I don't know how to fix it.
Client PC: Ubuntu 22.04.3 LTS running Remmina 1.4.25, Remmina VNC Plugin protocol
Host PC: Ubuntu 22.04.3 LTS with built-in remote desktop enabled with Legacy VNC protocol enabled (for my phone, which is not involved in this problem to my knowledge)
This is a relatively recent problem, but has persisted through months of periodic updates. It possibly started when I upgraded the host PC to 22.04.3 LTS, but I had enough remote desktop problems to solve at that time that I didn't notice it right away. It does not happen on my 2 Raspberry Pis.