Hi Tom,
Looks like a bug in MultipleAxesListPlot. Use CombinePlots instead, it is much more versatile.
p1 = ListPlot[data1Labeled, Frame -> True];
p2 = ListPlot[data2Labeled, Frame -> True, PlotStyle -> Red, FrameStyle -> Red];
ResourceFunction["CombinePlots"][p1, p2,
"AxesSides" -> "TwoY",
FrameLabel -> {"Punktabstand [\[Micro]m]", "Lebensdauer [\[Micro]s]", None, "ABC"}]
