A top (arguably, the top) metallurgist who studied previous failed parts told me it's corrosion of the Russian alloy used.
Corrosion is a hard problem in living quarters (ie moisture and salt) in space (sealed with no gravity)
I was wondering about this as well. In theory, there are also some metals and compounds that react with each other with just simple contact which result in some kind of amalgamation which can result in disastrous structural loss. Veratassium recently did a video on this kind of effect[1]. Could this be happening here?
It seems as though the leaks are always in the Russian section? Perhaps this is why. Humans are the weak link. Damn breathers.
In microgravity, everything gets everywhere. My mother worked on NASA funded research for diagnostic spit tests to determine chronic versus acute stress, which previously required blood draws, which are a less than optimal choice in space. It's all very stressful.