Outside of the concerns of 5G's effect on the human body, I have seen issues brought up about possible interference with other RF devices that operate close in frequency to the 5G bands. These are things that the FCC is supposed to manage but some of the critiques have been that the FCC is not doing enough. The ones below are about 5G potentially causing interference with GPS devices [1] and about the 5G band interfering with weather predictions because the 5G band covers the passive water vapor emittance bands. [2]

[1] https://arstechnica.com/tech-policy/2020/05/millions-of-gps-...

[2] https://geog.umd.edu/sites/geog.umd.edu/files/pubs/Benish%20...