No,it isn't a bug. It has always been that on android,using chrome browser or the youtube app meant that whatever google account was used in play store is also used to log you into google both on on chrome,yt,maps,etc...
They just brought that feature to desktop,I suppose now you'll be logged into whatever google account last used?
This includes payment info you inputted on the play store or anywhere else.
What exactly is your concern,I can't imagine you'd expect boundaries and privacy to be a thing google would respect with any of their products. They say "don't be evil" but they're pretty wishy-washy and flexible as to what they consider evil. I'd equate complaining about privacy and boundaries with google and fb to complaining about the rude staff and unpleasant patrons in prison.