will anyone be able to reveal whats under the white paint with a jpeg/png or any other type of screenshot?
In image formats that do not support Layers there are no hidden pixels behind the visible pixels.
so with a png/jpg screenshot they wnt be able to reveal what is under it in any way?
Not with this one.
If the painting was done with less than 100% Opacity or Fill it MIGHT be possible to discern some details but in this case the white is largely actually white.
Aside from that: If someone wanted to hide personal information for example that is their decision, isn’t it?
no this is not about somone i have sent something and was scared if they can reveal it in anyway possible.
and also does a png screenshot have layers?
A saved png can only have one Layer.
To avoid any risks with Brush Opacity/Flow you could create a Shape Layer (with the Pen Tool or Rectangle Tool etc.) and then merge that Layer into the Background.