I doubt it’s just one chemical, but various kinds of plastics and adhesives, and possibly some electronic components are all likely contributors. For example, o

I doubt it’s just one chemical, but various kinds of plastics and adhesives, and possibly some electronic components are all likely contributors. For example, on the 8th gen. iPad, the keyboard connector is surprisingly smelly. Heat increases the rate of offgassing, so a medium amount of heat in well power managed devices can draw out the time for which there is noticeable offgassing for years. I have found if you can burn-in a computer or TV with heavy load (and consequently heat) for say a month or two, that usually takes care of it. But some mobile devices (especially fanless ones) are “too good” at thermal management, making this difficult. And even for devices with fans, you want to run them in a clean environment so you don’t prematurely fill the fans up with dust or worse.