Qt with raspberry Pi 4 and DRM async errors

[SimoneCu]

Hi,
My goal is to have a full screen Raspberry Pi 4 application with QWebEngine support.
I've setup a Raspberry Pi 4 and successfully compiled Qt version 5.15.0 from source with options for opengl es2 and eglfs. Everything is working when using QT_QPA_EGLFS_SWAPINTERVAL=0, but dmesg is flooded by

[drm:vc4_page_flip [vc4]] *ERROR* Async flips aren't allowed

Beside that, everything is working. Is there any setup that can be done to avoid this flooding?

Note: I have tried using QT_QPA_EGLFS_SWAPINTERVAL=1, but the video is behaving completely wrong.