Regression, 2nd stage date/time dialog, the day randomly appears and disappears

a 0.4.15-dev-2534-geba00d1 gcc 8.4.0 win dbg build.
Self-Built using RosBE2.2.1, with a cleared output folder, reconfigured and rebuilt from scratch.

When the 2nd stage setup calls the time/date dialog,
the day "Freitag" is randomly appearing and disappearing.
0.4.15-dev-2534-geba00d1_2ndStage_DateTime.webm
0.4.15-dev-2534-geba00d1_2ndStage_DateTime.log (nothing is logged, when that happens)

This looks like a regression to me, I do not remember having seen that before (maybe introduced somewhen between January 2021, and 2021-05-14)