Yes, I know it's an infinity symbol. I took the screenshot from a user that uses Windows. I use iOS and couldn't find it. I did find something similar called Visual Studio but, it's different and I also looked to see if it was a previous Visual Studio app from long ago and still can't find it.
I did ask the laptop user and the said they didn't know what it was, and I was like....just click on it (in my mind).
They were no help...and I don't know them personally. They uploaded a video on youtube and was sharing their screen. That's when I noticed it.