Have you tried mining in spots/overlaps that are on the edge/outskirts of bubble?
I have some "hunch" - I had the worst results betwen patch3/4 in the most known spots - although they are still "pristine".
So it should not make any difference.
My 210t etc runs were on my way back from Crystaline Shards grind trip. Near the bubble, but not really in.
I would try to "hop" spots as much as possible on your place,
to exclude option that FD introduced some SECRET CHANGE again - one that is supposed to push us to SLOWLY expand our playground.
I know it's stretched, but it somehow fits the Tritium yield changes.
Enough to mine for a few jumps when we run ot of fuel, but no enough to travel far.
Just a "out of thin air" idea. I seem to try really hard to "rationalize" FD choices