Hi
@SkunkPunk! This looks like a Manganese deficiency, and it's probably related to your pH being not acidic enough during the previous weeks. Indeed, a high pH or an excess of iron can lead to this deficiency. Once you've fixed your pH to 6.2~6.5 the problem should be gone after a few days. Affected leaves won't recover but the new ones should be healthy. Hope this will help, let me know in the comments section if you need any further information. Happy growing! 👊