When you use default Samsung keyboard app, it logs your recent 20+ copied items. There is no easy way to disable it. Switching to Gboard keyboard (Google's app) and deactivating clipboard history there doesn't prevent Samsung to continue to log your history.
See screenshot below
(Switch to "Samsung keyboard" in settings if you dont use it currently, then long press to insert a text anywhere and hit "clipboard" to see your sensitive info or naughty past!)
Not giving user an option to switch history off is a very questionable practice from Samsung, in my opinion.