(Don't know what it is called)

[Boyish]

I am getting this

At the bottom you should see it

[Glenntech]

If you go into the phone app
Dial *#0*# into the keypad
At the top you have 3 different colour screen tests
If the lines dissappear in these tests. Then you are looking at an app or theme causing this
If the lines are still there on the tests
Then you will probably need the phone looked at

You can try Wiping the Partition Cashe on the phone. Sometimes this can help some issues

[Glenntech]

Wiping the Partition Cashe clears out a lot of old or corrupted information that can cause issues

Follow the steps below. You must follow every step and you should be done in about a minute

Turn off your phone.

Connect your phone with a USB cable
to PC or another Samsung mobile

You will see the charging icon on your screen.
Wait till it shows charging with battery percentage.

Next, press and hold the Volume up and Side key simultaneously.
You can press the volume up button just before the Side key.
The Samsung Logo followed by
Samsung Galaxy appears on the
screen.

At this point, release the keys
Phone will boot into Android Recovery mode

In Android recovery mode, using Volume keys, choose "Wipe Cache
Partition" .
Use the power button to accept that.
You will then see its cleared.

Then the top option, reboot phone.
Press the power button to reboot the phone and then sign in normally