MacBook dies unexpectedly

To give us an idea of your laptop's configuration and a view of the system log summaries, please run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper. Within the EtreCheck app, make sure to click the "Share" button and select "Copy Report".

Disconnect all external devices in case one of them is causing a problem.

After providing the EtreCheck report, you can try booting the laptop into Safe Mode and leave the laptop booted into Safe Mode when you leave the laptop overnight to see if it makes any difference. The laptop may have some limitations while booted into Safe Mode as third party drivers will not be running.

How to use safe mode on your Mac - Apple Support

Try running the Apple Diagnostics to see if any hardware issues are detected.

Do you leave the laptop running with the lid open over night? Do you log out or put the laptop to sleep at night? Do you close the lid at night? Do you power off the laptop at night? Do you leave any apps open & running over night?

When you boot the laptop in the morning after a crash, how much of a charge does the battery show as soon as you log into the Desktop (the battery level shown on the login screen may not be accurate so wait until you log in). If you connect the charger, then make sure to log into the laptop quickly because the battery can charge quickly if not checked immediately.