Node js concurrent DB I/O operations in mongoDB makes node memory frozen or fully occupied for certain process

NodeJS concurrent DB I/O operations in mongoDB makes memory frozen or fully occupied for one process. I'm not able read the DB queries when more concurrent write/read happens in the mentioned architecture which i've attached here in drive link. The memory frozen happens on any of the 3 services when the high load occurs.

https://drive.google.com/file/d/18Wkdv_gRzeW7LKrd-CdvTAyzjMLxtP5s/view?usp=sharing