It looks like this is related to Xrandr-based fractional scaling. That distributes the scaling responsibility between Xorg and Mutter (gnome- shell). It worked, but had some edge cases not dissimilar to this bug. To test this theory, you can try disabling Fractional Scaling under Settings > Screen Display.
Long term, the solution is Wayland native fractional scaling. While that does exist in Ubuntu 24.04, complete support for Nvidia with Wayland does not. Ubuntu 26.04 resolves all of this. If you are unable to move to Ubuntu 26.04, then a possible solution for 24.04 is to use only display connectors wired to the integrated Intel GPU and then select the Wayland session (not Xorg) on the login screen. You might be able to do that by avoiding the HDMI port and using Thunderbolt port adapters instead. As I understand it, the "Dell Pro Max 16 Plus" has two such compatible ports on the left side next to the HDMI port. ** Package changed: xorg (Ubuntu) => mutter (Ubuntu) ** Summary changed: - Wrong resolution on primary (laptop) screen after turning on external 4K monitor + [xorg] Wrong resolution on primary (laptop) screen after turning on external 4K monitor -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/2156353 Title: [xorg] Wrong resolution on primary (laptop) screen after turning on external 4K monitor To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2156353/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
