HSB Colorpicker sets 50% Brightness when color is "picked"

Via Tasmota’s web interface I set color to red with full saturation and brightness.


The corresponding log looks like this:
2020-10-21 15:12:13.923 [vent.ItemStateChangedEvent] - BTL_bulb_1_color changed from 359,63,100 to 359,100,100
When I open the colorpicker after an reload, it shows correct values:

After changing the color 1 or multiple times, brightness jumps to 50%.

The log does not give any hints in this:
2020-10-21 15:17:01.278 [ome.event.ItemCommandEvent] - Item ‘BTL_bulb_1_color’ received command 238,92,100
2020-10-21 15:17:01.327 [vent.ItemStateChangedEvent] - BTL_bulb_1_color changed from 359,100,100 to 238,92,100
2020-10-21 15:17:05.348 [ome.event.ItemCommandEvent] - Item ‘BTL_bulb_1_color’ received command 116,6,100
2020-10-21 15:17:05.427 [vent.ItemStateChangedEvent] - BTL_bulb_1_color changed from 238,92,100 to 116,6,100
2020-10-21 15:17:08.384 [ome.event.ItemCommandEvent] - Item ‘BTL_bulb_1_color’ received command 46,98,100
2020-10-21 15:17:08.424 [vent.ItemStateChangedEvent] - BTL_bulb_1_color changed from 116,6,100 to 46,98,100
2020-10-21 15:17:09.315 [ome.event.ItemCommandEvent] - Item ‘BTL_bulb_1_color’ received command 303,82,100
2020-10-21 15:17:09.391 [vent.ItemStateChangedEvent] - BTL_bulb_1_color changed from 46,98,100 to 303,82,100

Additionally, when the colorpicker is closed and opened again, it shows a white color:


Closing the colorpicker and reloading the page solves this issue.

So, from standard log events I don’t see a hint why the GUI misbehaves.
I tried to set log level to debug, but I’m flooded with logs in this case.