I will try my best to describe my problem with my poor english
As you can see on the screen, the copper GND plane is not filled properly.
As far as I understood, the problem here is the isolation between the two copper plane.
It is better in my opinion to switch KiCad into English to get screen-shots.
I think in clearances the higher should always win.
So if from net rules it comes that between 50V and GND nets should be at least 0.5mm and then you make zones for both of them with clearances set to 0 than 0.5mm should be still valid, I think
I don’t want to edit the clearance in the net because it will edit the clearance for all tracks and I only need less clearance for this specific plane.
For all nets (I have there max 3V3) I use clearance 0.2mm. But I add a netclass called HV and I put into that class my PoE (48V) nets and define for that class clearance 0.4mm.
For GND zone I specify 0.25mm clearance.
Now when one of my PoE nets is crossing through GND zone I would not like it if my high voltage nets for safety got 0.4mm clearance to everything but only 0.25mm to GND.
Parameter specified for smaller part of bigger thing overwrites parameter of that bigger thing.
Parameter specified for pad overwrites parameter specified for footprint and parameter specified for footprint overwrites global parameter.
But zones in gneral are not smaller parts of something.
I have not checked anything, so sure of nothing I have said.
Each zone and each net has a clearance setting, and when resolving the actual clearance, KiCad always uses the biggest clearance between the items. On top of that, footprints and the pads in them normally inherit the clearance from the net (netclass), but this can be overridden. You can also create custom rules to set clearances between some specific items. How the actual clearance is calculated in the end can be quite difficult to determine.
