Surfing behavior not being visible to other users is exactly the reason – the by far most important and absolutely towering reason – for private browsing to exist. Everything beyond that is nice to have but ultimately not really useful, not for what private browsing is actually used for by (most) actual people.

It’s not some side benefit, it’s the primary reason for private browsing to exist at all, at least as far a product manager (who actually understands and cares about what users actually want from their browser – so not actually a bad one) might be concerned.

That’s why I can absolutely understand how this kind of bug can creep in. The most important aspect of this feature (from the point of view of most people actually using the feature) is not that browsing leave absolutely no trace anywhere, the most important aspect is that browsing leave absolutely no trace where other users of the PC can see it†.

I’m consequently a bit confused why everyone is unpacking the big conspiracy guns. This seems like an easily understandable and completely plausible bug to me.