Weighted blankets seem to be one of the latest medical things to become mainstream(abused) a bit like the drug Ozempic. Originally they were for people with autism spectrum disorder.
They are quite a specialist thing and are made specifically for the person (and very expensive!) My son had one prescribed by his paediatrician when he was younger, he had to be weighed regularly as they are made to a weight ratio and had to be altered as he grew. They should only ever to be used up to 2 hours at a time or in times of stress and anxiety, it’s part of some people with autism needing to feel deep pressure to calm down or function and it’s a safe way to do it. He also had a weighted vest that worked well at school, but again only for short periods at a time.
Buying a generic weighted blanket and using it overnight etc probably isn’t the best thing for anyone to be honest