I can tell you, with 100% certainty, that at least in the case of Siptah, there’s at least one location causing server crashes. Having a base built at C-9, specifically near where they added a new NPC, is an example.

I can see how the performance issues from the new menu system could potentially be causing crashes on high population shared host servers, and I suspect it’s definitely contributing to the increased occurrences of people falling through the mesh.