

Alternatively, they could just charge to 80% and show that it is 80% charged, like iOS and macOS do.
edit: I seemed to have misread the comment above. It’s useful to not be lied too, in my opinion, because then you still have the option to charge to 100% when needed.
Don’t forget Shush from the Netherlands: https://shush-earplugs.com/about/ Their plugs are certified (2016/425 PPE)