Not sure the ADL is really a reputable organisation worth looking to as and authority on what is and is not hate. They're an explicitly zionist organisation with a history of defending genocide.

That said, this particular article seems completely fair. They don't say the ok gesture is a symbol of hate, only that it is sometimes used that way. Which is accurate.

But also:

Since the early 1800s, the gesture increasingly became associated with the word “okay” and its abbreviation “ok.”

Whoops guys, got that one wrong. OK is the original form, and okay is a lengthened form of that.