What is happening: When aging up (does not appear to happen between young adult and adult but have seen it between infant to toddler, toddler to child, and child to teen) skin details that aren't freckles are switched with a different skin detail that isn't freckles, including a different vitiligo pattern or birthmark. I have noticed freckles changing from one pattern to another, within the types of freckles, but I haven't yet seen freckles swapping to a birthmark or vitiligo. I've only noticed this with facial skin details, but it may happen with body ones as well.
What I believe should be happening: When a skin detail is applied it remains the same when the sim ages up if that detail is available for the new age group, and if is is not available for the new age group to not apply anything at all (for instance strawberry marks).
How to reproduce: Create a sim, child or younger, and give them a skin detail that is not freckles. Age them up in live mode either by waiting out the timer or by using a cake.
Mods?: They were all removed for the last update and while I currently have MC Command Center installed, the save I first saw this in has never been played with mods enabled.
