@Zyky I was also exploring this theory with some others at the same time as you, but I think that the 'outerwear causes the glitch' theory might not be correct, since I was able to observe someone jumping between different blocks while they were wearing the PSO2 Megumin Replica Outfit, which is not even layered wear at all, and they would randomly either load for others as cute and short as they had been designed, or sometimes completely enormous and distorted, almost at random.
We then took the experiment even further by dragging other people into the screenshot experiment who all took screenshots of each other and discovered that it's potentially happening at random to everyone, everywhere, but not always at the same time. It can even happen at random when a character is unloaded and reloaded for any reason, such as moving outside of someone's draw distance for a long time and then coming back, and even just from changing an accessory or outfit.
Aside from this glitch being extremely destructive to immersion, it also means that livestreamers on YouTube and Twitch may end up severely embarrassing SEGA when they inevitably discover live on camera that this glitch is happening everywhere in the game at random, all day, right now.
A particularly wild aspect of this glitch is also that when a character loads in and appears glitched to others, the distortion displays to them the character set to the palest possible skin tone that the game has, in addition to adding >10cm of height and making the character overall bigger. I probably don't need to explain the number of ways in which that is a public relations catastrophe waiting to happen.
It's definitely happening and it is everywhere, and it appears to be almost-random. SEGA needs to fix it now. Preferably it needs to be fixed yesterday. There needs to be another emergency maintenance.
EDIT: Additionally, the same randomness above is happening to weapon camos, which sometimes do not load for others. When a character is glitched as described above, there is a high probability that their weapon camo also will not load, thus leaving them holding the image of what the original weapon looked like.