Distilled water doesn’t really have a pH on its own. Before using it, you still need to adjust it for the plant. Growers use distilled water for its absence of stuff (low ec/ppm), not necessarily its pH.
This may seem counterintuitive, but at your next water/feed, adjust the pH to 6.3. Then carefully run enough through your pot to get about 25% run-off and checks its pH. If it has fallen to 7 or lower, then good, just keep proceeding with watering/feeding as usual, BUT ADJUST YOUR PH EVERYTIME.
If it went higher, you’ll need to do a real flush with pH adjusted water. Depending on your nutes, this is necessary about midgrow, anyway, but you’ll want to flush the pH to its proper range asap. Anything above 7 is absolutely too high.