GPIO toggling frequency

We use software SPI in XBee3.
At some point, the CLK frequency decreases 2-3 times.
The dependency was never established.

On the initially new module, the pin toggling frequency is about 500 Hz (it suits us).
Something happens and the frequency goes down (similar to changing the clock frequency of a controller).

Flashed up such a code.

from machine import Pin

PIN__SCLK = “D1”

sclk = Pin(PIN__SCLK, Pin.OUT)
while True:

After several experiments, it was possible to establish that downgrading the firmware version restores speed.

Product: XB3-24;

Function set: Digi XBee3 Zigbee 3.0;

Firmware: 1009(and lower) - D1 frequency 500 Hz
Firmware: 100A(and higher) - D1 frequency 100 Hz

How increase D1 frequecy at 100A firmware?