The system settings window become blurred when the font settings page opens in KDE 6

Fedora 40 with KDE 6.0.4:
Everything on the system settings window become blurred (not only font, and blur greater font smoothing) when the font settings page opens. If disable the font smoothing on this page the system settings window return to normal. If enable the font smoothing the system settings window return to blurred again.
Fedora 39 with KDE 5.27:
This problem doesn’t exist.

What could be the problem?

OS: Fedora 40 with KDE Plasma 6.0.4
Monitor: TV LG 4K (4096x2160), connected by HDMI
Videoadapter: AMD Radeon 6700 XT