DIY liquids are harmful?

I bought DIY liquid costs only 20€ but doesn’t taste i mean it’s very light. I was reading some videos on youtube and people in comments were saying that DIYs are very harmful for lungs. I don’t know if DIY and normal liquids make any difference in this. Any advice? I am in Paris, so it would be great if you guide me what to buy and from where. I need large liquids to save money as i don’t want to buy a new liquid every week.