Hi since my last sudo dnf update I run into this issue when I try to open my Monero gui wallet.
qt.qpa.xcb: could not connect to display
qt.qpa.plugin: Could not load the Qt platform plugin “xcb” in “” even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
I was having this issue as well and was able to fix it by turning off Wayland for the Monero wallet using Flatseal.
Hope this helps!
edit* I made an assumption you are using the flatpak version of the Monero GUI wallet.
this command fixed the issue for me
flatpak override --user --env QT_QPA_PLATFORM=wayland org.getmonero.Monero