Why not just start new context? From documentation:
A context corresponds to set of independent incognito pages in a browser that share cookies, sessions or profile settings. Pages in two separate contexts do not share cookies, sessions or profile settings.
so for people comming across this staying in Incognito modus when you don’t want that in the script test driving so to speak. (then you know what I’m talking about)
very long story short, The solution was:
use latest SeleniumLibrary
use Microsoft Edge, with MSEdgedriver. Problem solved.
(and then I don’t need the fast switching option anymore)