QT6's app's edges show weird gaps and flickerings on Gnome Wayland with fractional scaling

All QT6 apps on my computer show flickering edges or gaps near the bottom/right edges. This seems happen only when I use a fractional scaling value like 150% or 175%, not when using 100% or 200%. 

It is not a bug of those QT6 apps, because when I ran simple Python QT6 example code that shows a simple window, that window also had the same flickering edges and gaps.

QT5 apps are not affected (probably because they are using XWayland, not native Wayland). This problem began to appear only in recent months, but I have changed my GPU from AMD to Intel Arc, so it may or may not be related to that.

That artefacts do not get recorded in screenshots taken within the OS (i.e., the screenshot looks different from what I actually saw on the monitor), so I had to use my physical phone to record the monitor.