What could be making a loud metallic clang in apartment building at night

I know this is an unhinged stupid post because nobody could possibly know what exactly is happening at some random ass apartment but

It's 4am and the sound is happening again. It happens every night between 3-4am. A loud metallic clang that echoes around the building (I think it's near my floor, but not on my floor), a few seconds to a few minutes between each clang. Maybe 2-10 clangs total. It's a loud sharp fast sound almost like something metal was released from a spring/tension to hit another piece of metal.

I have heard doors slammed and bumped around before and it isn't that. Nor is it a dull thud of like a door being kicked.

I am so curious to try sneaking out to see what it is but also bit scared.

Anyone else experienced similar and what it could be?

My current theories:

1) the dumpster for the trash is being moved to be emptied at this time. But idk I thing it's too far away from my room to make a sound so loud, and it seems to be echoing around from inside the building, not coming from outside it.

2) the elevators have some kind of midnight maintenance mode/cycle idk that involves some clanging

3) some unhinged muppet is indeed out there snapping large sheets of metal together

Any other ideas??