Possibly same issue: https://forum.pso2.com/topic/11967/ngs-not-using-correct-character-model-for-base-pso2-characters-when-viewed-by-another-person
@FoolsArcana said in Character Model Bugs?:
but a lot of my pso2 outfits (Outfits specifically) fit the NGS model very oddly.
What do you mean by this? PSO2 outfits can't fit the NGS model, using a PSO2 outfit swaps your character to a PSO2 body (and same for NGS outfits). Your character's body is defined by the outfit being worn. However, there's a "slider sync" setting in the salon (because NGS and PSO2 bodies use the sliders a little differently) that could possibly change it, by making it so that when going NGS->PSO2 outfit it attempted to set the sliders to something than they actually were on your PSO2 model originally.
If your char looks pregnant, are you using the old type 2 idling animation? In PSO2 the female (now type 2) idle animation had them jut their stomachs forward and if you weren't careful it was really easy to get a similar look. It may just be that it's less pronounced on NGS models because of how extremely thin they tend to be.