A new small icon appeared

[mm201545mm]

Hi everybody, I love you all.
My device is galaxy A50 with android 9.0.
A few days ago I've noticed a small new icon at the left-down corner . the icon changes by opening apps. when I tap it the app info appears on the screen of the app on the icon.my question is:
1.does any one know why does this icon appear?
2.Is a built in one or a third party one?
3.what is the function of it?
4.Is it possible to remove it from the screen and how?

 

[mm201545mm]

this is an attached screenshot of the ocon

 

[mm201545mm]

and another one

 

[GameTheory]

this is an attached screenshot of the ocon

I'm going to assume that is a third party app you installed that is showing that icon. That is a generic icon provided to app developers for testing their apps. I don't think Samsung would use such a generic icon in the final consumer product. If they did, shame on them.

Edit:
I see you added more screen shots which would change my answer above. So never mind.

 

[Steven58]

It seems to me that the icon below is an app running in the background. The first one looks like Android Forums' icon. I've never seen that before, fyi.

 

[mm201545mm]

Thank you all

 

[ocnbrze]

its called smart popup view. it is found in the advanced settings (at least in my note10+):

smart pop up view:
"receive notifications as icons that can be tapped and expanded in pop up view"