Extremely harmless UI elements got moderated and temporarily deactivated my account?

Images in question were just one button with a price, the rest were simple boxes with flat colours. How does this violate ROBLOX TOS? And what can I do to prevent such warnings in the future?

Were the assets made by you or from the web?

Everything was entirely designed by me alone.

99% of the time when assets get content deleted it’s due to an automated system Roblox has in place. Most likely this automated system had a freakout and decided to moderate your assets, it’s not unheard of. There is nothing you can do about it that’s worth your time, I suggest just accept it as is and move on, although maybe don’t try and upload the same assets. If the issue persists and your assets keep getting moderated then contact support.