5G gets the techno-utopians in HN all excited about the possibilities of [INSERT THE POINT OF 5G] and they'll get mad at anything that threatens its introduction.
You can find PHDs who believe just about anything (I saw one recently with a sign saying "sunspots cause global warming"), and PHDs publish papers. So you have to look at whether they were peer reviewed, in what journal, and what the findings and methods really were.
It's a lot of work to properly evaluate studies, but I think that meta-analysis is easily abused in this arena. The other big problem is the null publication bias. Have one hundred people roll dice, and if you're only interested in snake-eyes and only publish papers on where that happens, you'll get like 9 studies where they rolled snake-eyes and one responsible scientist who publishes a null result, and conclude that there's a 90% chance of snake-eyes on dice rolls...
I feel like the most damning lack of evidence is the lack of correlation between cell phone adoption and the purported ill effects. In the last 20 years pretty much the whole world started holding RF transmitters up to their head, from basically zero beforehand. If there was an effect, it would be epidemic.