Currently Scribus uses org.kde.Platform 5.15-21.08 runtime which depends on older mesa (org.freedesktop.Platform.GL.default 21.3.9) while newer ones are available (runtime 5.15-22.08 and mesa 22.3.2).
Thanks for the update.
Sorry I forgot about it, I've had an issue with other flatpak app using (buggy) mesa from older runtime event though it was built with newer one.
Currently Scribus uses org.kde.Platform 5.15-21.08 runtime which depends on older mesa (org.freedesktop.Platform.GL.default 21.3.9) while newer ones are available (runtime 5.15-22.08 and mesa 22.3.2).