Safari showing bookmarks from Google Chrome
I just had the same happen to me, and likewise I prefer to keep my work and personal bookmarks separate. I was searching through menus and preferences when I noticed the small pop-up message at the bottom of the Favorites page display that asked something like "Favorites showing bookmarks and recently visited from Google Chrome. [Keep] or [Do Not Keep]" so I clicked on Do Not Keep and it all went away.

I don't like not being able to undo something, so I was looking for where in the settings or preferences this could be toggled, but alas no luck so I guess it's permanent.