I suspect that’s something that would need to be brought up either with the developers of the specific program that handles keyboard inputs or languages, if it cannot be changed in general. Or with the individual Desktop Environment projects that create the GUIs to change the underlying settings, if that setting just is not exposed graphically. Unfortunately I don’t know what those would be, but maybe it can help point into a more precise direction for further research. I doubt that it is an issue that goes as deep as the Linux kernel being involved. (Take it with a grain of salt though, I’m mostly speculating.)
I suspect that’s something that would need to be brought up either with the developers of the specific program that handles keyboard inputs or languages, if it cannot be changed in general. Or with the individual Desktop Environment projects that create the GUIs to change the underlying settings, if that setting just is not exposed graphically. Unfortunately I don’t know what those would be, but maybe it can help point into a more precise direction for further research. I doubt that it is an issue that goes as deep as the Linux kernel being involved. (Take it with a grain of salt though, I’m mostly speculating.)
Edit: in a quick search I found this thread with a possible solution: https://forum.manjaro.org/t/trying-to-change-dead-key-behaviour-im-stumped/85029