gc.collect() does not work properly

I am running MicroPython v1.20.0 on 2023-04-26; ESP32S3 module (spiram octal) with ESP32S3

import network
from machine import Pin, I2S
import urequests as requests
import struct
import gc
from debugfun import breakpoint

gc.enable()

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
if wlan.isconnected():
    wlan.disconnect()
wlan.connect('SSID', 'ssidssid')

sck_pin = Pin(12) 
ws_pin = Pin(13)
sdo_pin = Pin(14)

audio_out = I2S(0,
                sck=sck_pin, ws=ws_pin, sd=sdo_pin,
                mode=I2S.TX,
                bits=8,
                format=I2S.MONO,
                rate=44100,
                ibuf=8192)

buf_size = 4096
buf = memoryview(bytearray(buf_size))

while True:
    print("Free RAM:",gc.mem_free())
    text=input('>Say:\n')
    text = str(text).encode("utf-8")
    text = ''.join('{:02x}'.format(x) for x in text)    
    response = requests.get(url=("http://xxxxx/?d=" + text))
    data = response.content
    print("Data size:",len(data))
    i = data.find(b"data")+8
    while i < len(data):
        buf = data[i:i+buf_size] 
        i += buf_size
        audio_out.write(buf)
    del text
    del response
    del data
    del i
    gc.collect()

The Free RAM get lower after every loop. I have deleted all variables created in the loop so I think it is supposed to be a constant free memory.

Start by reproducing the provided loop on an ESP32S3 with MicroPython v1.20.0 and recording gc.mem_free() across iterations. Compare the memory behavior around requests.get(), response.content, I2S.write(), and gc.collect(); done means identifying the cause of the declining free RAM and confirming a fix or documented limitation.