Well it's to be expected, as your character has a lot higher values for the non-modded people they would actually see the default maximums possible but it should not affect what others see in any major form, just try to run the game without the slider mod and your character will magically turn into a more vanilla-like body, just keep in mind anything beyond the game's default limits would be usually maxed out for the game and if you "save changes" your character will revert to the game's basic values
No i just changed the boobs size thanks to the breastsize mod, everything else (waist, legs, belly...) is the same as how i created my char at the start.
And i asked to an other player and he too was seeing my character with a "chubby" shape and not with the skinny basic game skin.
So as Alcaster said :
That's because they got crappy servers.
So the game renders your char of default values then finally gets the actual values.
An other problem is the underwear mode feature (which has nothing to do with the nude mode by the way). I tested it with an other player and we couldn't see each other in underwear while in town (safe zone) despite that in our respective screen our own character was effectively in underwear mode (you can switch on/off via the gear window). So i asked him to follow me in my characters house and here, it was working as intended : we were both in panties for each other.
Normally this mode allow you to show your underwear in any safe zones. Not only in a house.
It's a huge issue given how expansive is it to buy outfit, even just underwear.