Understanding Attach Actor To Actor

Hi There,

i have a question regarding Attaching an Actor to an Actor in Multiplayer Games.
I found out, that the character starts jittering, when you run a standalone game and you attach the character to another actor.
To show you what i exacly mean, i have prepared this video:

My concern is to attach a character to another actor, that the character e.g. can grab up a wall and the wall began to move around, when a Character is attached.

My question is, why the attach Actor to Actor function causes these issues when the character is moving.

I hope you can help me! Thank you alot!