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

If you own a kindle reader you can just connect it via usb and dedrm the kfx files.

To play devils advocate here, a bad translation of the post might interpret the first half of the sentence as “they should keep murdering you” instead of “even if they keep murdering you”. But it’s Facebook, so they could also just be on the fascists’ side.