It was just a "fit test" apparently, making sure things fit together properly. Super Heavy Booster 4 appeared to be missing a skirt around the bottom, and had a lot of plumbing on the engines just hanging out in the wind. The tower isn't done, it's missing the catch arms and crane to recover & mount the rockets on the launch pad. The fuel farm isn't done, with at least five tank covers that aren't installed yet. Ship 20 still needs heat tiles fitted to the outside. The rockets still need to be pressure-tested, cryo-tested, and static-fire tested.

Can't wait to find out what it's like when 29 engines light up. It'll be like the eruption of Krakatoa. I think the USSR failed to develop a manned moon rocket with a similar design having many, many engines. The number of failure modes with so many engines pushed the risk up too high. But this is 2021, not the 1960s, so that might not be an issue anymore.

The landing with be a nail-biter, whenever they get around to that. The relatively short grid fins don't provide much leeway for lateral & rotational accuracy on landing. I would have done something like a tail hook & cable system that fighter jets use to land on aircraft carriers. But so far, SpaceX has been successful with their designs. There's always more than one way to do things.