Increasing memory usage of simulation of quantum circuits in a "for" loop with Qiskit

Question

I have the following code:

from qiskit import QuantumCircuit, transpile
from qiskit_aer import AerSimulator
from qiskit.providers.fake_provider import FakeMumbai
import resource

    
backend = FakeMumbai()
sim = AerSimulator.from_backend(backend)
shot = 1000
num_samples = 1000
for s in range(num_samples):
    qc = QuantumCircuit(4)
    qc.measure_all()
    transpiled_circuit = transpile(qc, sim)
    sim.run(transpiled_circuit,shots=shot)
    print(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss)

where the resource part is only to check the memory usage. As the loop goes on, the memory usage increases. Why?

For this kind of circuit we still talk about few bytes, but I have this problem also for larger circuits, and, in that context, the script terminates.

I have already tried with del and gc.collect() without results.