small horizontal lines on screen

Hi,

It may be dead pixels on your MacBook Pro LCD screen. Try to contact Apple Support or make Genius Bar reservation if your local retail Apple Store is open or find opened Apple Authorized Service Provider to be examined your MacBook Pro there.

Official Apple Support

https://www.apple.com/retail/geniusbar/

Apple - Find Locations - Location Selector

Take it to a apple store and get it checked before the whole screen goes dead.

better to take it now.