Hans van der Meer via ntg-context schrieb am 19.11.2023 um 11:56:
> I should have a first page without pagenumber and pagenumbers on the 
> subsequent ones.
> However the MWE here introduces an unwanted blank page from the call 
> to \setuppagenumbering[state=start].
> And the \setuppagenumbering has to come after the \page, of course.
>
> Should I program otherwise?

There is nothing you can do here for the moment, the empty page is caused
by a new piece of code in page-lay.mkxl (see below) to go to the next 
odd page
when you use the \setuppagenumbering command.

page-lay.mkxl (line 1436):

\appendtoks
     \ifnum\realpageno>\plusone
         \page[\v!odd]%
         \setuplayout
     \fi
\to \everysetuppagenumbering

Wolfgang