Red Shelf use triggers mod mark even when deleted before saving to library

[MadameNordica]

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? 1.61.15.1020
What expansions, game packs, and stuff packs do you have installed? Get famous, get to work, seasons cats & dogs, city living, get together, parenthood, dine out, spa day, mochino, laundry day, toddler stuff, perfect patio, backyard stuff, holiday (freepack)
Steps: How can we find the bug ourselves? Use the Red clutter shelf content to place and item delete the shelf save your build. you'll find your build is now marked as modded, even though there is nothing modded in the build.
What happens when the bug occurs? the game marks my build as modded, even though there are no custom items left in the build
What do you expect to see? I expect to NOT have my build marked modded when I use the red clutter shelf and subsequently delete it before saving
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? No

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This just started happening today. I've spent the entire day trying to fix this build and have been unable to.

[crinrict]

@MadameNordica I tested your house and removing the Peter Pan pictures removed the modded flag for me.

I don't think those are game content ? Not sure.

[Entoarox]

Since a few patches ago, custom paintings (created by "Paint from reference") are also treated as custom content for newly uploaded builds, most likely this is the cause of your "custom content" flag rather then any actual custom content.