Half moon sign on screen

[RAIN]

See my screen shot. I got half moon type edge on inner side of screen.
on my new 4 day old J7 PRO.
same type was there on my old S3 Neo
but that I have not bothered. As it happened after using two years. guide me . please.

[RAIN]

I find out. One application name clipboard was effectively doing so. I uninstall same application from my both phone that sign has gone.
Thanks for your concern.

[Prasad0507]

which are the third party applications. give complete list...