The piece is 72869 Bar Holder with Clip and 90° Angle (Mechanical Leg)
It's a new part for 2021, and as the name implies, one of it's main uses is as a leg on various creatures. It seems especially well-suited for building spiders:
It hasn't had many other official uses to date, but it does get used as a robot of some kind in the Marvel advent calendar:
Here is a related video: What is inside a Powered Up Large motor
The video shows how the motor is being opened. There is no screw or opening to do this. So, I have to use knife and Philip screw driver. The result is - the shell of the motor was damaged.
The objective of this mission was to check what is wrong with the motor since it could not be detected by ...