[bug] DPI Scaling Issue on Ubuntu Linux (Wayland)

[TheNotoriousF14]

Describe the bug

This problem is similar to issue #5600, but given the time gap between the two reports, I expected the developers to have already fixed it. The issue: when the application renders, the fonts, components, and UI elements get rendered at a lower scale than expected — likely due to incorrect DPI scaling.

You can see this more clearly when you zoom inside the app using your laptop touchpad once you zoom in (maybe another ‌bug): , the blurriness and pixelation around elements become very obvious. If you reload the app while still zoomed in (and without zooming out), everything returns to normal and the resolution looks correct. But as soon as you fully zoom out back to the default scale, the problem comes back. This is exactly what I observed. Note that this bug didn’t appear on all elements, but it affected most of them. *This bug appeared on both dev and build mode.

How I fixed it (temporarily) : You can either run these environment variables before launching the app (in both dev and build modes):

export WEBKIT_DISABLE_DMABUF_RENDERER=1
export WEBKIT_DISABLE_COMPOSITING_MODE=1

Or you can add the following code to your main.rs file:

use std::env;

fn main() {
    env::set_var("WEBKIT_DISABLE_DMABUF_RENDERER", "1");
    env::set_var("WEBKIT_DISABLE_COMPOSITING_MODE", "1");

    myApp_lib::run();
}

Reproduction

No response

Expected behavior

To fix this bug and also find a way to prevent zooming via the touchpad

Full tauri info output

[✔] Environment
    - OS: Ubuntu 24.4.0 x86_64 (X64) (ubuntu-xorg on x11)
    ✔ webkit2gtk-4.1: 2.50.1
    ✔ rsvg2: 2.58.0
    ✔ rustc: 1.91.1 (ed61e7d7e 2025-11-07)
    ✔ cargo: 1.91.1 (ea2d97820 2025-10-10)
    ✔ rustup: 1.28.2 (e4f3ad6f8 2025-04-28)
    ✔ Rust toolchain: stable-x86_64-unknown-linux-gnu (default)
    - node: 24.4.1
    - npm: 11.4.2

[-] Packages
    - tauri 🦀: 2.9.1, (outdated, latest: 2.9.4)
    - tauri-build 🦀: 2.5.1, (outdated, latest: 2.5.3)
    - wry 🦀: 0.53.5
    - tao 🦀: 0.34.5
    - tauri-cli 🦀: 2.8.3
    - @tauri-apps/api  ⱼₛ: 2.9.0 (outdated, latest: 2.9.1)
    - @tauri-apps/cli  ⱼₛ: 2.9.4 (outdated, latest: 2.9.5)

[-] Plugins
    - tauri-plugin-fs 🦀: 2.4.4
    - @tauri-apps/plugin-fs  ⱼₛ: 2.4.4
    - tauri-plugin-opener 🦀: 2.5.2
    - @tauri-apps/plugin-opener  ⱼₛ: 2.5.2
    - tauri-plugin-http 🦀: 2.5.4
    - @tauri-apps/plugin-http  ⱼₛ: 2.5.4

[-] App
    - build-type: bundle
    - CSP: unset
    - frontendDist: ../dist
    - devUrl: http://localhost:1420/
    - framework: React
    - bundler: Vite

Stack trace

Additional context

No response

[FabianLars]

If these env vars fix it this very very likely means that it's an upstream issue.