i would get to an Apple Store to get this looked at ASAP! You have a display assembly issue!
As long as you don’t have any blemishes on the system they should replace your display either under warranty (depending on your coverage) If you have a service contract (AppleCare+) and if you press they should be willing to give you a warranty exception!
Make sure your system is spotless no dirt or oils on the screen or body. Warn marks are not an issue (palm rest or keys shiny) Arrive with your system in a padded case. Let them tell you what they can offer you. They may tell you its not covered. Then politely explain how you use your system and haven’t dropped or banged it. If they still say no ask for the manager and be polite (honey goes farther!) I also find going mid morning on a Tuesday or Thursday work better as they are not spent from the weekend or burn’t as its the end of their week. If you are still getting a no press to speak with the store manager and keep going up. I wish you well in your coming battle!
If you just can’t get this resolved by Apple or your system has damage then you’ll need to replace the display assembly your self MacBook Pro 13" Two Thunderbolt Ports 2019 Display Assembly Replacement and fork over the ~ $450 USD for the part - Ouch!