Custom keyboard mappings

I have a PC with Linux Mint 19.2 installation that I set up a while ago. For that system, among other similar modifications, I figured out a way to remap one specific key combination: Meta + ~ produces a ` (grave accent). Recently I built a new PC with a fresh installation of linux Mint 20.2. I carried over all of the modifications that I thought I'd done to the old system into the new one. This includes: - /usr/share/X11/xkb/keycodes/evdev - /usr/share/X11/xkb/rules/evdev.xml - /usr/share/X11/xkb/symbols/us All my modifications work on the new PC, apart from the grave accent one. Apparently, this particular setting is done elsewhere. I checked the modifications of the desktop keyboard mappings: dconf dump does not reveal anything related to the accent key. Basically, I need to reverse engineer how I managed to remap that key on the old system. It would be really great if someone could give me a hint either how to configure such mapping or where to look for the possible other modifications I could have applied on the old system outside of what is available in /usr/share/X11/xkb/.