The Rothschilds used a red star of david to represent themselves in Frankfurt, and came to use it as their family name, which translates as "red shield". Since they are described as being one of (or the top of) the 13 illuminati bloodlines, I thought it was a representative symbol of many conspiracy theories.

Sure, there is also the connection of Israel / Mossad to 9/11, that's also represented in the "dancing Israelis" pic beside the star.

But another interesting thing that came to mind, was that I read a while back how whatever Rothschild heir (Evelyn?) was actually in his penthouse apartment on 9/11 (with a view of the towers), and how it was described as odd that he was, like he went out of his way to be there that day... I think it was supposed to be his honeymoon actually... I can't quite remember exact details I googled but couldn't find the article. Maybe that description will trigger a memory in someone with a better memory than me...

EDIT found it: the anecdote about Evelyn de Rothschild is in the long documentary "Ring of Power: Empire of the City"

https://youtu.be/2zldDedsFuk