This is a red flag. If I were you, I'd be concerned. Requiring you to keep your camera on all day is not normal for most reasonable companies. Yeah, some employers ask for camera on during meetings or when working with confidential info, but constantly? That's really pushing into privacy violation territory. You're not in an office where your boss can just look over - this is a whole different level of control. Plus, it's basically impossible to do normally anyway: people eat, go to the bathroom, sometimes work looking messy or not in office clothes - and that's their right at home.
From a legal standpoint it depends on your country and labor laws. In Russia, for example, you could challenge requirements like this through the labor inspection office as a violation of privacy rights. But the main thing is - think about whether you want to work for a company that doesn't trust you like that? If they're already setting these conditions from the start, it's usually a sign of major corporate culture problems.
I'd either suggest talking it through directly with the employer (maybe it's just a contract thing or only for meetings), or looking for different work. Remote work is good precisely because of the freedom, not total surveillance. There are plenty of normal companies that treat remote employees fine without that kind of paranoia.