Could be this yellowing on newer leaves a light deficency problem?

Those look like micronutrient deficiencies.. they show up in new growth. Make sure you have a solid spectrum of all micronutrients. I recommend the Photone app instead, if you’re willing to pay for the in app purchase. I’ve seen it compared directly with the 0 apogee instruments par meter - it’s within 10% of any deviation from the apogee meter. It gives a read out in PPFD umols as well rather than lux.