It wasn't a health concern. The only concerns for 5G were long-term practicality, energy and service costs and shorter coverage.
5G was supposed to be made for robots, IoT and wireless home internet.
I haven't tried 5G, but it seems that the expected speeds would be the same as 4G in early days.
My understanding of 5g is that it was going to be rolled out in Western countries like it is in China, but then there were "security concerns" regarding huawei so they stopped building towers and started selling high speed 4g as 5g. I have no idea where I heard this from though so it could be all incorrect