Yellow leaves

not light burn, so if you liked the internodal spacing before, move the light back to same distance as before. yellow leaves at top can actually be a toxicity or deficiency. I'm not familiar with platinum organics, so i can't guess as to strength given. the thinner blades of newer growth makes me think K-tox or P-tox... more likely K-tox based on typical NPK ratios for pot. Give it a second. if it clears up, figure out which part of your fertilizer provides the most K and reduce its portion slightly. or, feed a bit less overall than you were previously... every plant is different. get used to this process of trial and error. it gets easier if you are systematic about it. nutrient calculators can help you add up ppms from labels (i have a spreadsheet in week 7 ggxww, but not verified for liquid nute calculations, should be, lol, but you can download it if you want.) know what you feed. it helps immenseley later on.