Windows 11 laptop won’t sleep, stays awake all night

Unlike the older S3 sleep state (which completely cuts power to most components), Modern Standby keeps your PC's network connection and some background processes active so it can wake up instantly, like a smartphone. In theory, this should still use very little battery. In practice, a buggy driver or an app can force the CPU to stay active, leading to the fan running and severe battery drain you're experiencing.

In Control Panel > Power Options, set When the lid is closed” to Sleep, and in Device Manager, disable the Allow this device to wake the computer option for all USB devices.

Try this:

Open Control Panel > All Control Panel items > Power options > select your power plan > change plan settings > Restore default settings for this plan.

See if it helps you.