Q.Why the leaves of my prayer plant turn yellow?
I water the plant twice a week, as soon as thee soil has dried completely. It isn’t exposed to sunlight directly. I spray the leaves with water for extra moisture 3-4 times a week. However, some leaves keep turning yellow, but new leaves keep growing back.

Certified GKH Gardening Expert
As long as you are certain that all other conditions are as should be, then the most likely diagnosis is that it lacks humidity. This can be especially true when using air conditioning, as it draws moisture out of the air.
This article will explain common reasons for the issue that you are having: https://www.gardeningknowhow.com/houseplants/prayer-plant/brown-leaves-on-prayer-plants.htm