Weird picture-in-picture websites on Safari

Weird “sub windows” showed up in Safari

I really wish I had a screenshot for what actually happened, but I was trying to save an image in Safari on my 13 Pro, and it was being a pain—I think I double tapped on it or something, but suddenly the webpage shrunk down into a little rectangle and just kind of sat on the screen in front of the browser. I went into my tabs and whenever I tried to go to other website, they got added to the little rectangle and the number of websites added to the little rectangle showed up in the top right of that rectangle.

It persisted even when I went to my Home Screen, until eventually they just….went away.

No clue what feature this is or what it’s for or how I even triggered it.

Sorry for the vague description, but does anyone have any idea what that could be?

It almost looked like an old “picture in picture” thing. Sort of like THIS screenshot, but with a number in the top right.

[Edited by Moderator]