It’s a metaphor; the fig leaf is the symbol of Judaism, of which Christianity was, at first, considered a crazy fringe cult offshoot (Christians thought Jesus was the messiah, Jews not so much.) What Jesus is saying (or, more likely, what an author with an agenda is saying Jesus said) is that the Jewish religion has beautiful, enticing promises but, overall, bears no fruit and should wither and die.

A huge period of that history was spent trying to gain a foothold as both a serious religion and a mainstay within the Roman Empire … so you see a lot of “The Jews fucked up this” and “Whatever the Empire says is good is an abomination before the lord thy god (pride, lust, passion, envy, etc.).

Interesting… but frustrating. (Also a good example of business as usual for organized religion)