It might not actually cause harm or strange effects to people's bodies, but I'd certainly feel better if it was tested and used by doctors in a hospital and not some "spa" since those tend to be poorly regulated and where all kinds of quackery takes place (https://www.aafp.org/afp/afp-community-blog/med-spa-industry...).

The safety of the device itself is a concern, but so is the trustworthiness of the output. Midjourney already has some very questionable history with medical imagery (like this totally legit image of rat testicles published in "Frontiers in Cell and Developmental Biology" https://upload.wikimedia.org/wikipedia/commons/c/cc/AI_gener...)