The War Zone has an interesting report on the shock diamonds [thedrive.com] produced by the engines of the Starship rocket during the recent launch attempt.
"When you typically see a shock diamond or a mach diamond, it can be from like a jet engine test, or a single rocket nozzle test. [When you] look at those up close… you see the same shock diamond effect on the smaller scale."
"But what was interesting, specifically about this case [the second Starship launch], is you had 33 engines firing together, which you would kind of intuitively think would make for a pretty messy environment. I think close up [this] is probably true, there's some complicated dynamics happening there."
Additionally, the article features a passel of pictures of the launch.