The Fun is
Japan has a C-Band 5G that goes to 4.1Ghz and there's been no issue there.
( they just made sure the main lobe from the antenna was not pointing down a landing strip )
Europe has the same C-Band... and there's been no issue there.
( nothing was done here... because of the EU power limitation in mobile phone antenna emissions already in place since 2/3G )
So the FAA twisted panty from my point of view is just a knee jerk reaction after the 737Max Debacle ( and they probably have a few other skeletons in the closets waiting to explode ) and the fact that US Airlines fly old planes bought on the cheap.