As you increase light, plant processes increase.
Photosynthesis (assuming you have CO2 and H2O present in sufficient qty 6CO2 + 6H2O → C6H12O6 + 6O2) CO2 yes, H2O good?
Respiration
Other stuff
I think you might be looking at an issue in the root zone that is exacerbated and only shows up with higher respiration.
Also your RH is a bit high making VPD a bit low, meaning the stomata are open but there is so much water in the air that there is not good gas exchange. If you increase the lights, temp goes up meaning RH goes down, VPD goes up, so respiration is restored. In that scenario, if your nutes were out of balance or not enough O2 in root zone, it could look like this and it is not really PPFD doing it, but rather the higher leaf temps and lower RH.
I'm thinking that if your VPD was on point and your watering / nutes / root zone oxygenation was all perfect you could bring that light way up.
It's a friggin balancing act man.
TLDR - I think the problem is actually in the root zone.