Odd UI behaviour Painter 2023 and MacOs 12 and 13

The odd thing I noticed right from startup is that Painter 2023 does not have an application container, i.e. the Desktop is visible except where there are menus, bars, windows or panels, etc..  Please see the linked screenshot. Feels very awkward so I hope this is not a design decision.  When focus is shifted to a different program Painter "disappears" from the Mac's windowing and the only way to return to it is to select if from the Dock or Cmd-Tab to it.  And no way I  can see to change what desktop it is running other than quitting, moving and relaunching.

I have experience this on both my systems:.

    Mac mini M1, Ventura

    iMac Intel, Monterey

There are some other things that simply do fit into the Apple HIG or generally expected behaviour, but this the big on that, at for me, actually impacts usability. 

Is this just the way Painter is on MacOs or do my systems have demons?

All the best,