Regarding Charging

Hey, so I bought a new MacBook Air M4. I’ve heard online that if you use it while charging, it stops charging at 80%, and the power is drawn directly from the adapter after that. But in my case, it just keeps charging — the last two times I unplugged it at 93% and 88%.
Is there any feature that makes it stop charging at 80%, or was what I heard online incorrect? Or does it take some time for the MacBook to learn my usage patterns and adjust accordingly?

if it stops at 80% then i will use it with external monitor , keyboard and mouse because it takes 15-20% per hour while them being plugged in else i will use it normally like a normal laptop user.