PCBNew - filled zones don't respond immediately to layer opacity change

Description

If I set layer opacity to 100% filled zones stay around 80%. If I decrease opacity for that copper layer, filled zones seem to keep that delta and always have lower opacity. There is no visible change in opacity from around 20% to 0%

1. Set layer opacity to 100% and look how it affects your filled zones
2. Try to lower opacity and verify how it affects tracks vs zones

KiCad Version

Application: Pcbnew

Version: (5.99.0-7320-g00edc85f4f), release build

Libraries:
	wxWidgets 3.0.5

Platform: Windows 10 (build 18363), 64-bit edition, 64 bit, Little endian, wxMSW

	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8)
	Boost: 1.73.0
	OCE: 6.9.1
	Curl: 7.71.0
	ngspice: 32
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=OFF
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
	KICAD_SCRIPTING_ACTION_MENU=ON
	KICAD_USE_OCE=ON
	KICAD_SPICE=ON