The sheets of stainless steel appear to have separated at the joints. This says the sheets are stronger than the joints, meaning they're overweight :-)
They're experimenting with 3mm steel instead of 4mm steel. A test tank they've built already passed an initial pressure test on 26 Jan.
One Starship requires 15 rings, a nosecone, a bottom and tanks. If they would all move from 4mm to 3mm then that would save a lot of weight. About 7-10 tonnes according to [1].
I was thinking something similar myself (more on weld quality, "welds should be as strong as the rest of the material"), but then I realized that this doesn't matter, and having an unoptimized test vehicle a week earlier is always going to be the better option for SpaceX.
A static weld is usually stronger than the base metal under static conditions (i.e. not undergoing dynamic shock loading). Welds are created at 3000 degrees C with 50-100C metal right next to it. By the time a weld cools there are always captive stresses, meaning during a failure the weld is the most brittle part. This can be alleviated with pre and post weld heat treatment, but there are always stresses built into a weld.
This is 4k slow motion and it is gorgeous. The giant sheets of stainless steel floating down at the end are noteworthy, among other details.
Michael Bay has nothing on Cosmic Perspective + SpaceX.