Memory usage increasing with direct vpc to cloudsql

When I switch from connection by /cloudsql/myproject:… to the private IP with the new VPC direct to cloudsql (Postgresql) the memory usage of my cloudrun instance is immediately growing a lot, like doubling. And then stable (it’s not a memory leak).

This is on all the services, that can be a Python service or a Go service with regular and quiet traffic. If I switch again to /cloudsql/myproject:… it came back to half.

What’s happens ?

Here a graph that show the bump even without traffic just using the private IP.