Yellowing leaves spots

Just went through this with my DWC OG Diesel Kush autoflower. It was a salt build up blocking nutrients( to much excess nutrients). You need to flush and give it a fresh feeding. I tried adding cal-mag, grow, bloom, Epsom salt. Nothing stopped it, took me a week to figure it out. Set your pH according to your grow medium. You should know, its easier for me to flush and my plants because I'm in DWC hydroponic buckets. You'll be flushing your medium so it's harder on the plant.

It’s a ph issue causing a deficiency. Get your ph in check and the plant will be able to uptake the nutrients it needs! Good luck ✌️🏻💚🌿💨

Seems like it's a Potassium or Magnesium deficiency, or even both (from the leaves I see in the background). It's hard for me to suggest a solution because I don't know what you're working with in terms of medium and nutrients. But overall I'll suggest to check your NPK ratios and make sure you stay as close to 2:1:3 as possible to avoid any mistakes.