Specific combinations of character creator items prevents ALL Minecraft worlds from loading entirely

A few weeks ago, I stopped being able to load any/all Minecraft worlds. This included local worlds, my two personal Realms, my friends' Realms, joining friends' worlds, etc.

This happened exactly the same way on 3 different machines (Windows 10 desktop, Windows 10 laptop, and Xbox Series X). It happens the same on completely different networks as well. It affects everything, but most of the testing is done by using a (new) basic vanilla world (i.e. Play => Create World => Create New World => Create).

Everything would get stuck in the same way. It would sit at Loading... (approximately 1/4 of the way through) and eventually it would timeout.

Local worlds give the error message "Unable to connect to the world. Please check your connection to the internet and try again." Realms give the error message "Disconnected from Server".

With the assistance of Minecraft Help, I now know the exact problem.

Oddly enough, the issue was originally caused by this specific set of character creator items:

• Tops: Dark Sweater - By CubeCraft Games

• Bottoms: Dark Warden Leggings - By Teplight

• Outerwear: Tainted Void - By Waypoint Studios

• Headwear: Pulsating Void - By Pixelbiester

• Gloves: Void Hands - By SandBlock Studios

• Face Items: Dark Monster Mask - By Spark Universe

I have now found quite a few other offending sets. I can reproduce this with entirely distinct item sets. It takes a bit of work (and trial and error) to build a set that reproduces the issue, but it's not exactly hard either. It seems to be the more complex pieces that contribute to the issue, so I'm looking for particle effects, overall increased size/complexity, Headwear and Face Items that would overlap, any item that goes outside the normal boundaries of the item slot, etc.

I'd lean towards this being some sort of progressive overload that eventually fails. Because it seems like you have to use a full set (or nearly fully set) of complex items to get it into the state. And from (limited) testing, I believe removing any one of these items will resolve the issue, rather than it being caused by a specific item in the list. But that's conjecture at this point.

Another possible option is something akin to clipping, where perhaps it eventually can have trouble with too many overlapping items.

Any use of the offending sets will 100% reproduce the issue. There's no ambiguity. The offending sets can be loaded or recreated in any character slot, and it will always cause a complete failure to load any and all worlds.

Under no circumstances should this prevent Minecraft from working entirely. Particularly for a local world. And it completely shuts down all play, which is the larger concern here, with very vague circumstances and errors.