I thought the point of making them like this was that they technically are reusable, so they can sell them (to people who for some reason keep buying them and throwing them away!) in places where disposable vapes are banned.
I had elevated white blood cells counts and I developed an autoimmune condition a few months after quitting vaping. I had good health record leading up to it and no family history of any autoimmune disorders. White blood cells eventually normalized but autoimmune is forever, although it's under control and I'm lucky that it was caught early.
In the final ~4 years of vaping I didn't use any flavorings either, just 70/30 mix of VG/PG and nicotine.
It's not terrible as far as vices go, much less harmful than the alternatives, but it's definitely not as harmless as I thought going in. I wish I hadn't started and went for the ADHD assessment right away instead of subconsciously self-medicating with nicotine.