ESC's are very noisy as they are generally either PWM or simple square waves of varying widths, and are of 730 thousand volts or more for these motors, constantly changing depending on commands or stabilization of drone !
tbh, sensitive electronics of any sort are vulnerable to even unrelated frequencies and just a strong EMF field propagated can interfere, plastic or carbon being no shield. digital electronics of course much less affected than analog, but remember many things eventually become analog (power) and thus can be affected in the analog domain.
if not for the 'clock' in digital, which is the 'gate timing' for reading an input, then digital itself would be affected even moreso.
a 'voltage' of EMF of any sort can 'look' like a signal to be processed, thus many elec devices are tested both in a faraday cage and in a reflective/normal room to cover best and worse cases, IF a real engineering endeavor.
distance and cooling and shielding is always a good thing !!