Where is the evidence of bees and birds dropping from the sky? All I see is somebody moaning in a video without much foundation. At present 5G is only using the 3.4GHz band and 4G has been operating in a similar band for years (as have other services), although 5G seems to be using even less power.
The biggest proven threats to bees / animal / plant life right now is our pollution of the environment (chemical), disease, changing climate and farming chemicals.