You need a magnetometer for stable yaw values. The MPU6050 does not have one.
they can read yaw quite reliably.
Then they use some other external reference for yaw. A gyro alone cannot determine the yaw angle.
why can't a MPU6050
sorry, you're wrong
Good to know, and I wish you the very best of luck with your project!
Now the MPU6050 has a 3D Gyro, so it must be able to retrieve the rotation round it's horizontal forward (x)
See reply #2