Hi,
yesterday there was an update of several qt6 packages. One of them was qt6-webengine (to 6.9.2-1). Using this package kmail does no longer render email contents - the window remains white. This affects the built-in window and the window I get when double click an email. Downgrading qt6-webengine to 6.9.1-3 fixes the issue. I am running wayland, my graphics card is a radeon RX590. I am not sure what is the cause of this misbehaviour: rendering with my specific graphics hardware? Bug in qt6-webengine? Maybe, this behaviour has the same cause: since ~ 2 weeks I cannot longer use brave-browser-nightly. Many parts of a webspage are blank, no contents. Using brave-browser (stable) this issue is not present.