“Edit - additional information- my realm has no experimental features none of those holiday or anything. And after now getting the same corruption on my local world (as well as a marketplace world) im confident this is not directly related to my packs or my worlds. I also- spent all day yesterday having to reload and reformat all my packs, and even with the world stripped of every single bp rp and bp rp “history” jsons.. the players still had the glitch speed. I reapplied original old simple bp rp and still glitch, and i applied updated bp rp and still glitch speed. The only way to get a world to stop the glitch speed is load a old world file previous to the glitch event. I do suspect its a player json glitch event that causes the initial glitch, as u can follow my comment that states the marketplace addon “morph into mobs”. But this world breaking glitch cant be corrected by fixing the file or the event that caused the glitch. The world becomes corrupt in some way.

Will get more info and get others to help describe shortly. Im surprised i didnt find any reports on this allready as i have seen this on many of players worlds.

Problem-
Players who join the realm have ludacris speed! No effect status or particles. (Includes my moderators so i know its no hack client. ) they can often run through walls or blocks, and often cant interact with most things or players. Resembles spectator mode but players are visible and can interact with some things.
The speed cant be slowed by effects.
The speed effects “that player” everytime they join!
The speed doesnt effect every player! It seems players that join the realm before the glitch starts are ok even after the glitch event. After the glitch event all players have the issue.
I reloaded a new “copy” from my local worlds that does not have any issues. And moderators that “had” the glitch no longer have the glitch. But new players that join at some random point in time seem to develop the glitch.
Player json and other files have been checked and work appropriately, and other players worlds have had this issue as well.