I’ve been struggling with making the armpits of this shirt less janky, re-doing the weights, vertex paint, double-checking the uv_1, and it wasn’t until I ran it through TS4 CAS Tools that I got any kind of improvement. I don’t know what witchcraft CAS Tools is doing, but I won’t question it, haha (images are before/after CAS Tools)
I’m a little conflicted about accepting this mesh the way it is, but I think it’d be a better use of my time to accept it and start working on the other LODs/textures than to be stuck on a little jank that is only even apparent when the arms are up high like this (which is hopefully not too often? unless your sim is doing a lot of dance battles)