If you're using max-memory-mb, that applies to every process:
https://docs.rstudio.com/ide/server-pro/r-sessions.html
The max-memory-mb setting controls the maximum amount of addressable memory for R sessions (by default memory is unlimited). [...] Note that this value sets the amount of virtual memory that can be used by a process.
In other words, if you're setting that to 50GB, each session (and job) will get 50GB.
RSP uses ulimits to police resource usage, and these are per process by design. If you want to enforce a limit that spans a collection of processes (such as all R sessions and jobs run by a user), you'll need an external tool such as cgroups: