I have made a short tutorial on how to fix certain weight painting problems with armpits that can be a pain to solve! Because of the zoi models A pose instead of T posing when you apply weight in Blender, Blender often applies the weight in the armpits irregularly and causes very annoying visual glitches.
This is a quick how-to-fix it! Let me know if it was useful for you.
. I’m new to modding and only made small props so far so if I ever dabble in clothing, this will be very helpful