@vibhor30564 we really would need to see what this all looks like. Post some good pictures of that with your Question.
It is possible that this is a bad display. It can also be a bad connector (check for corrosion, broken and bend pins) Finally, it is possible (unlikely) that this is an issue with the circuit board. Start with a new display.
Since iFixit does not yet have a guide for this, use the one [https://www.nadiemellamagallina.com/en/manuales/smartphones-1/motorola-43/motorola-moto-g9-power-1290/pantalla-completa-11498|from here] Replacements are readily available at plenty of online stores.
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
Repair is War on Entropy!