Sim vanished, mouth remaind, then restted to base game

Product: The Sims 4
Platform:Steam-PC
Which language are you playing the game in? English
How often does the bug occur? This was the first time I saw it
What is your current game version number? 1.108.349.1020
What expansions, game packs, and stuff packs do you have installed? I have all packs except for Batuu Game Pack and Castle Kit
Steps: How can we find the bug ourselves? I have no idea...before this happens, I had my sim use the toilet but she started walking into the river underneath her penthouse in Ciudad Enamorada... she was completely out of map and walkable areas so I had to reset her using testingcheats on and a little after this, the bug occured so MAAAAYBE this was the cause of it?! But I'm not sure.
What happens when the bug occurs? My sim completely disappeared and only her mouth remained in live mode (photos attached) and in the sim panel where she is shown next to other sims but her portrait (when the sim is selected) in the panel, showed her completely vanished, mouth including. I went back to manage world... she was just a mouth or should I say, teeth... and I reloaded back into the game... she was back but her clothes, shoes, nails, make-up and eye lashes were completely resetted to base game stuff. Only her hairstyle and her tattoos remained unchanged as far as I could tell.
What do you expect to see? My sim as I styled her to be...
Have you installed any customization with the game, e.g. Custom Content or Mods? I only had MCCC at the time and the mod to put birthday candles on wedding cakes. I'm not a heavy mod user but I can't retry this bug without the mods either, since I don't know how to make the bug occur again.
Did this issue appear after a specific patch or change you made to your system? I'm not sure but my game is completely up to date and I have NEVER seen this bug before despite years of playing the sims 4 so I assume yes.

Edit By Crinrict: Removed tag