You can disable raw input in mouse settings to "fix this" for now.
For default minecraft launcher you need this.
Make folder 1.14.1_lwjgl3.2.2 and in this folder file 1.14.1_lwjgl3.2.2.json with this: https://pastebin.com/raw/r4Xq3ZPs
They have different names by default and there is sha1 and size check, so if you change it like that it will get overwritten. You need to modify json.
You can try using this: https://raw.githubusercontent.com/Dinolek/LWJGL-MultiMC/master/3.2.2.json
Edit Instance -> Version -> LWJGL 3 -> Customize -> Edit -> Paste this
LWJGL 3.2.2 fixed this problem, mouse sensitivity is increased a bit now.
They downgrade lwjgl from 3.2.1 to 3.1.6 only for linux to fix this.
@Pokechu32 no, I was talking about this issue.
@Azarilh Namu It is under "Options...">"Controls...">"Mouse Settings..."->"Raw input", at least in 1.14.4.