High cpu usage with hidden systray icons

Not normal cpu usage with hidden systray icons when there is any hidden item and the applet is showing hidden items.

CPU consuming:   (1)   (2)   (3)
panel-14-systra  0.0%  8.3%  50.3%
Xorg             0.3%  9.6%  98.7%

(1) applet not showing hidden items 
(2) applet showing hidden items 
(3) letting the mouse pointer over the icon "<"

versions:
xfce4-panel-4.16.3-1.fc34.x86_64
xfce4-panel-4.14.4-3.fc33.x86_64