The KDE kirigami apps flickering

I don't really know where to report the issue, so I try here:

1. Install ktrip and/or kitinerary from flatpak
2. enable some providers from your region
3. search the route
4. enter to some details of connection
5. enter back, play around some time
6. when regreting to the list of connections the screen begins to flicker: turns black and when touched with the finger it flickers with a proper image one time, then black again. On the list of task of phosh appears a black window too

As the bug uppears only on flatpak versions of programs, it should be related with some video output issue