https://bugzilla.kernel.org/show_bug.cgi?id=202873
--- Comment #4 from Thomas (v10lator@myway.de) --- Kernel 5.0.5 still flickers. Anyway, after watching this more closely I'm pretty sure it's the same bug (the text cursor for entering username/password causes flickering on SDDM, for example). Still it seems to be fixed by deactivating the second monitor.