I'm unsure of behaviour in firefox, but at least for me chrome at work will keep session information for the private window until chrome is closed completely no

I'm unsure of behaviour in firefox, but at least for me chrome at work will keep session information for the private window until chrome is closed completely not just the private window. Having said that anecdotally I'm sure google do ip/wifi network tracking as after I was connected to a friends wifi network while he was in the process of moving house I began being served ads for moving companies even though I had done no similiar searches or visited related sites.