Chlorosis and spots. Recently, I noticed that the leaves started becoming more faded. veins became more visible in green, and then spots started appearing

Calcium deficiency and starving for both phosphorous and potassium. Older damaged leaves will not recover, no matter what you do, you can only slow/stop it from progressing further. Increase the frequency of cal/mag and add a P/K booster to your fertilizer line up, or increase the dosage if already using a P/K booster. Symptoms will take 10-14 days before they stop appearing..........be patient.

This looks like a bunch of different symptoms. In one pic it looks like n-def. In another k-def, and in another maybe Mg-deficiency. So, is your pH in a good range? Did you spike any "1" element's concentration recently (last week or 2)? either you need to make significant adjustments to balance of your fertilizer or you have caused some sort of lockout - pH or one element is inhibiting others.