This is likely just an input processing issue in the app. Try Gedit, scrolling is smooth there. Some information is lost from the input events when going through Xwayland so I'd expect X11 apps to be worse. Sublime text has decent scrolling though, so the VS code problem might be an Electron issue. How does it work on a normal Linux workstation? Is scrolling smoother there?

It seems like X11 apps are treating a trackpad scroll like scrollwheel clicks -- they can only scroll ~3-5 lines at a time, nothing more fine-grained. When scrolling with trackpad, I expect to be able to scroll by very small amounts.

Gedit works perfectly well as you mentioned, but Sublime Text has the same issue as other X11 apps (eg. VS Code, Emacs). Sublime Text will scroll ~3 lines at a time, though it animates as it scrolls which helps mask it somewhat.

No X11 app I've tried gets precision scrolling, including Chrome/Firefox despite them apparently supporting it:
https://bugs.chromium.org/p/chromium/issues/detail?id=384970

See also: https://pavelfatin.com/scrolling-with-pleasure/#linux

Talking with reveman, xwayland may need to be updated to support this. From the article in #3: "This API happened to be XInput 2.1 Xorg extension which introduced high-precision scrolling events. The API is available since Xorg 2.12, and since version 1.7 the touchpad driver uses the new API."

@dgreid, any thoughts who could look into this?

We have XInput 2.3 in our build of xwayland so looks like xwayland is not limiting this. Testing with 'xinput test-xi2 --root' also show high precision events over XI protocol so I think it's just application support that's missing.

It seems pretty rare that applications support this. Firefox seems to support it but you have to set MOZ_USE_XINPUT2=1. Chrome doesn't seem to support it and I guess that also limits all electron apps. Maybe that's something we can fix relatively easy.

I recently marked the Linux touchpad events to precise event on X11.
https://chromium-review.googlesource.com/c/chromium/src/+/988748