Long story but there is a list of cards called the "reserved list" and WoTC promised to never reprint them. So they got cheeky and said "well, we didn't really reprint them because they aren't legal, see?" Oh, and pay us $1000 for these cards.

https://mtg.fandom.com/wiki/Reserved_List

One of the most famous cards is on the RL:

https://scryfall.com/card/leb/233/black-lotus?utm_source=mw_...

And the new "not legal" version:

https://scryfall.com/card/30a/228/black-lotus