icon in foreground stays visible, how to remove it?

Hello!
I visited pages around
Google Developers Blog: Introducing Learn, your key to unlocking Google’s educational content for developers

And now there is an icon on the screen in foreground, which I cannot remove.
The Icon shows the text
Learning experience...

Have anybody an advice for me?

Thank You
Erhy
wih Win10 Prof 2004

Post a picture.
Maybe I'm wrong ... but I suspect that this icon is not an icon. It sounds like a graphical artifact.
But a picture would help.

margrave55 said:

Post a picture.
Maybe I'm wrong ... but I suspect that this icon is not an icon. It sounds like a graphical artifact.
But a picture would help.

This is always in foreground of the screen:

Ghot said:

That sounds like you picked up some adware. I would try a Malwarebytes AdwCleaner scan...
https://www.malwarebytes.com/adwcleaner/

Thank You!
I applied Adwcleaner.
Found something more and the icon is gone.
Erhy