pHain in my... Recommendations for resolving high pH issues?

Hey all, I have some crazy numbers coming up on my Marquette this year. Our harvest chemistry was right where we wanted it- pH 3.36, 24° Brix, TA 11.2 g/L. However, after fermentation and ML, we're now getting a pH of 4.28. That's FOUR POINT TWO EIGHT.

Our best guess is that with an extremely rainy July, the potassium levels skyrocketed and we're seeing the results of that now. Any other ideas how this might have happened??

Also looking for solutions. We can acidify using tartaric, but in bench trials we found that at a 3.9 pH, the wine tasted much more acidic than we wanted. Is there anything else we could do to bring this wine back in line, or is it destined for blending?