My problem is exactly what the title says. Sometimes my brightness controls (fn + up/down error) stop working until I restart my computer. My guess is its some service that stops working for whatever reason. Shortcuts is registering that i´m pushing the “increase/decrees brightness” keys.
OS: MX-Linux 23.4 KDE
Hi! One caveat I’ll give right away is that MX Linux does a lot of things its own way, so I would suggest also checking in the MX Linux forums if you haven’t already 
When the Fn keys stop working, does the brightness control in your system tray also stop working?
Are you using systemd with MX Linux?
Some information about the graphics cards, drivers and displays on your device will likely be helpful too - running inxi -G provides a good quick summary of that.