Not sure what is implied with “Aviation systems working with 5G came way before telephone companies”. The 3.5GHz allocation for 5G (bands n78 and n79) was part of 3GPP Release 15 which was only frozen in 2019. RA’s did not have to contend with 5G prior to this date. The main issue with RA’s is that the out of band Rx and Tx have a very shallow rolloff and may be Rx sensitive to tower transmission on the upper end of the channels used for 5G. This is unfortunately a systemic problem on RA’s which have designs based on dated (but time-tested) electronic designs.