as the name suggests, it was first synthetized in 1999 and only now the public got to know about it - that's 24 years and we know about it only because of human spite
Patents start from the day they are applied from, right? They just kept it secret until they applied for it. So the patent starts from 2020.
Anyway, I wonder how important that patent https://patents.google.com/patent/KR20210062550A/en is in the end, as it seems their way of manufacturing it is not very effective anyway and it might even be possible to find nearby compounds with similar properties.