The city that my 90+ yo grandmother lived knocked on the door and said they were looking for multiple families living in her house she told them no one was living here but her. By the time they were done she had to remove the gas oven in her basement and stay over beds she had for us to visit.
She wouldn't let all of us visit in a group anymore. She was a nervous wreck about it for years and this probably didn't help her dementia that set in a few years later.
If she had followed your advice she would've lived longer.
I don't think it's formaldehyde but something is different. It burns different. I'm speculating. Last week I was thinking it felt like certain vaccines or rubbing alcohol was inside. There's the reports of known eugenics proponents releasing GMO mosquitos and using malaria mosquito releasing drones on the Russians. Malaria reports might be caused by the illegal immigration. They could be "vaccinating" us with the mosquitos.