Many people running larger motors on x8 setups and using the onboard BEC on the Matek F722-HD or similar FC have reported the video feed from the air unit freezing during aggressive flying.
It isn’t the current draw of the air unit that causes the issue, it’s the lack of capacitance before the FC regulator which is unable to cope with the voltage fluctuations from 8 motors and active braking. If you have smaller motors ie 2806.5 on 6s then some people have reported no issues when using the BEC on the FC, personally I wouldn’t risk it. With larger motors ie 2812 on 6s it is certainly a bad idea to use the FC BEC or one of the Matek/iFlight micro BECs. The solution which most operators have gone for is a D36V28F12 Pololu with a 390uf 35v low ESR cap on the input side of the Pololu.
For 8s rigs a separate lipo to run the air unit is recommended
Here is where you can get the required components:
https://www.pololu.com/product/3786 – US
https://proto-pic.co.uk/product/pololu-step-down – UK
https://www.ebay.co.uk/itm/183673621998 – Caps UK