So I've grown tomatoes for a few years now and I'm getting the hang of it fairly well. One thing I can't figure out, most varieties seem to have a thing where there'll always be one or two small branches (like the ones that are maybe 6 inches long or less and quite thin stems, nothing major) in the process of dying. If I left the plant totally unattended for like a month and came back I'd guess there'd probably be 5+ small dead branches that just turned yellow, then brown and dry in out of nowhere. Solid organic fertilization schedule, not watering on the leaves, no excessive rain/cold/heat, none of the fungicide/general vegetable plant disease control sprays work, organic or not. It just seems to be an unstoppable process of small branches gradually dying.
It seems worse on determinates, for sure. But they also just end up basically dying off if you leave them anyway so I don't worry about them. Indeterminates it's a little annoying.