Ask for an error of MPU 9250 with Madgwick filter!

Dear all,

I am coding for MPU 9250 - 9DoF using Madgwick filter.
This is source code for Madgwick filter that I am using.

However, it had the error as shown on the video below. The pitch, raw, yaw always increase although I have not rotated the IMU sensor.
Link video shown the error: - YouTube

I also tested as the tutorial as the link below (I have not changed any thing) but it had the same issue as the video result.
Link tutorial:
Link video result: - YouTube

Could you help me to find and fix this error?

Thank you so much for your help!

Please post your code here

Yes, this is source code of my project. I am using arduino to read data from IMU sensor. I tested for both kinds of sensor MPU 6050 (6 DoF) and MPU 9250 (9 DoF). However, it is the same issue.
Link my project:

And source code for arduino is attached below!

Thank you so much!

simple_raw_mpu_6050.ino (1.06 KB)

mpu9250_arduino.ino (4.08 KB)

Can you help me for this error?