I’m half French so it’s all good. I just found the one copyediting mechanical before I kinda realized the typos were deliberate:

1960s is abbreviated ’60s

Apostrophe, not an open quote like ‘60s which is the Medium default (they should know better) or even 1960's or 60's or even as I’ve seen ‘60's

Unless you are saying ’60's music, which is terribly awkward and better off being said: the music of the ’60s.

Basically, the 19 is what is being abbreviated, not the plural case of the decade.