High memory usage in Node.js Express API

We are having a high usage in our Node.js Express API, the API be idle sometimes and the usage be like 500MB+ for hours even though no one is using the API, We assume that Prisma ORM might be causing the issue, but not sure exactly, we have a cron jobs running with node-cron but it's only running late at night when no one is even awake to use the API, we don't have a lot of traffic to begin with so why the memory usage is so high?