Back in my teenage years, my sweat would kill strings within weeks, but that seems to have changed now that I'm older - strings don't die on me nearly as fast. However, I recently bought a new SbMM Axis, and the strings it came with were creating dirty spots all over the maple fretboard. A little Dunlop 65 got rid of the stains (the fretboard has a stain polyurethane finish). Sounds like that's your problem, although since I changed the strings out for a new set of EB slinky 9's, it hasn't come back.
EB makes string cleaner wipes - have you tried running those across your strings immediately after you put new ones on? Perhaps the strings have some sort of oil or lubricant residue on them from manufacturing that isn't getting completely washed off?
In addition to diet, perhaps air quality where you live? Has your air been more polluted lately?
Otherwise, EB makes coated strings. That was my solution when I was younger.
2018 EBMM Axis BFR in Steel Blue
2020 SbMM Axis in White
2021 SbMM Axis in Neptune Blue
...and some other, lesser, non-MM guitars.
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