Suspicious Player Flying, Disrupting Matches and Missing From Player List

[Jruizm14]

Today I encountered a suspicious player in Slendytubbies 3 Multiplayer and managed to record what happened.
The player was using a long, seemingly random username (something like "asdmajsdnsjafknjas"), but their character appeared as "Player" in-game.
What caught my attention was that this player wasn't showing up in the player list, despite being present in the match.
I also recorded them flying around and disrupting the game. I even spoke to them in the in-game chat.
When I asked what they were doing, they replied "idk" and "random shit". I've recorded video showing the incident, including the player's behavior, our chat conversation, and the player list. I'm not sure how they managed to do this, but I wanted to share the footage so others can take a look.
Video evidence:

Bro, this is even worse than the darkness fran incident back in 2.5