I think they did something in the 1.6.1 & 1.6.2 firmware, I never saw it on my drones until the firmware was updated.
It has only done it a few times, and it is possibly caused by outside interference - few times happened with the Anafi plugged in to the computer USB, and other times near a power station & power lines.
And that response from Parrot is pretty poor - clearly this never happened before and it is a new thing which is occurring with the new firmware, so at least acknowledge that and say why to re-assure the customer that there is no hardware issue.