Px4flow in auto mode

Hi dears,
I configured the Px4flow module following the ardupilot wiki and tested it in loiter mode. The test results were also acceptable and almost stable. My flight controller is pixhawk4 with 4.0.7 copter firmware.
in auto mode with a mission, the vehicle has some additional drift, and strangely it passed the point of the home and did not land (lost it).

ardupilot wiki:
https://ardupilot.org/copter/docs/common-px4flow-overview.html
https://ardupilot.org/copter/docs/common-optical-flow-sensor-setup.html#common-optical-flow-sensor-setup

A picture of the RTL path that is affected by drift.