@Srta_Kitsune Thank you for the information and screenshots. I don't use Mods or CC so I cannot recommend a program. It may well be that if you have any CC in your game, even if you don't use it on that particular sim, your upload will be tagged for the CC.
You could try removing your current Mods and CC plus delete the localthumbnailcache.package file in your 'The Sims 4' folder... Then see if the CC has cleared out by seeing if an upload to the gallery of a household then shows no CC tag. It the CC tag has gone, then try a different posing Mod without any of your current Mods/CC in the game and see if the CC tag is gone when sharing to the gallery.
I will ask some other helpers to see if I can find more information on this and edit the new information into this reply if I find anything out.