The Eachine EF-01 I got the other day is quite sensitive for interference caused by the motors. Image quality deteriorates quite bad and sometimes it gives the receiver a hard time in that it looses synchronisation completely.
I experienced this a lot on my microbuild based on a JJRC JJ1000 frame with 0720 motors and a H8 mini flight controller. The camera mount is based on the Whoopinator except I did snip off the protection brace because it did not work in ninjaflex (too floppy).
Here is a simple LC filter which will filter away most of the power supply ripples caused by the motors and the FC. Dropoff frequency (3dB) with the components listed in the schematic lies around 7.3khz. This seemed to be the sweet spot where no interference patterns were seen on the receiver side anymore. You can use other values and as a rule of thumb for both the inductor and the capacitor use a value bigger than the ones in the schematic if you don't have the precise values at hand.
(Schematic: battery is shown as two cells, but I actually use only one. The EF-01 is depicted as Rload in this diagram)
A little piece of copper EMC foil tape provides the input terminal. One end of the coil connects there, the other end connects to the positive terminal of the tantalum capacitor.
The JJ1000 housing provides enough room next to the control board to store the filter. For extra protection I covered the filter in some expoxy to relieve mechanical stress.
The image quality improved tremendously. The EF-01 has a really good image quality in tiself due to the 800tvl camera sensor. It is also working great in low light. All-in-all the EF-01 is a great FPV camera. The LC filter makes it a lot more pleasant to use.