Over the past six days I've been having a lot of notifications suddenly happening again. Most of the time it's not even when I've been browsing. One of them, however, I distinctly remember it happening while I was browsing: the notification specifically stated that it was from that site, and I went back to it to double check, and got it again, so I blocked that page from ever being gone to again - hopefully.
One of the notifications happened immediately when I opened Chrome, too, and it picked up where I left off with my pages. Two tabs at minimum were YouTube; I don't remember if I had any other tabs open.
But as I did say, most of these were happening at random when I was not browsing or loading any websites. The sites were already loaded. I was just scrolling and reading, or watching a YouTube video, or playing a game, or hell, just chatting to people on Discord/Skype with Chrome open at the same time.