Hello, thanks for reaching out.
This looks like a display issue, and could need a repair.
Although there is a few things you can try on your end, and save yourself sometime.
The first thing you can try is hard restarting your mac, to do this hold the power button on your mac for at least 5 seconds and should power off your mac, then power on your mac like normal by pressing the power button again.
If this did not fix it try booting your mac into safe mode:
Hold the power button for 5 seconds to shut off.
Power on and hold the Shift key down when you hear the startup tone. This should perform a safe boot.
If you see a screen with button, select safe boot.
Then boot up and check.
If this did not work I am afraid this is a hardware issue and you might need to see an Apple Technician or a 3rd party repair shop.
But before you do this, I have a few questions to possibly assist you farther.
Question 1: What MacBook model is it? To do this click apple logo in top left > then go about this mac > then check what model you have (Example should be like this: "MacBook Pro (14-inch 2021)"
Question 2: Do you have any Apple Care for your product?
Question 3: Did you get this computer used or new?
Question 4: How long have you had your mac now?
Hope this helps,
Cheers,