Q.Night Blooming Cereus Has Some Red Blotchy Patches On Some Of The Leaves

Certified GKH Gardening Expert
It could be leaf scorch. Is it in full sun outside? Try giving it a little shade in the hottest part of the day. Make certain you aren't overwatering and the soil is well draining. If you think it might be overwatered, change the soil using cactus soil.
Overfertilization can also cause discoloring. These articles should help pinpoint a problem:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/night-blooming-cereus/night-blooming-cereus.htm
https://www.gardeningknowhow.com/ornamental/cacti-succulents/scgen/saving-dying-succulents.htm