Yes, when you hover over the very edge of the Safari (any in many other apps) window, the sidebar will trigger for you!

Now for many years I have had this issue. It became more prominent in my ChatGPT.app where the sidebar would somehow get triggered automatically. I thought it was a bug, but it’s actually a feature. Usually I slide my cursor to the edge of the screen out of the way and apparently I was hovering over this area since I maximize most of my apps.

Not only that you can even drag the sidebar into not existing anymore by simply dragging it towards the edge of the window and it will go away! 

Go ahead, hide a sidebar in an app (try Finder) and hover near the edge of the window. 

It’s a feature!