Desktop is blurred on second monitor when no windows are open in KDE 6

Fedora 40 with KDE 6.0.4:
On second monitor (TV is connected by HDMI) plasma panels, plasma menus (except for the kickoff menu), icons and icon’s labels are blurred when no window (Dolphin, any application or kickoff menu) is open. When open one or more windows of Dolphin, application or kickoff menu the plasma desktop elements become sharp (no blurred). When minimized all windows and kickoff menu the plasma desktop elements become blurred again.
Fedora 39 with KDE 5.27:
This problem doesn’t exist.

What could be the problem?

Monitor 1: monitor Xiaomi 2K, connected by DP
Monitor 2: TV LG 4K (4096x2160), connected by HDMI
Videoadapter: AMD Radeon 6700 XT
OS: Fedora 40 with KDE Plasma 6.0.4

This only appears on Monitor 2 if the frequency is above 60Hz. At 60Hz and below there is no blurred desktop when it clear.