In your experience, what do you think it is?

Your plant has become slightly stressed. Which makes him reach for his nutrition.. But that wasn't present... Hence your spots in your leaf. You no longer get this from the leaf but just give normal food where everything is in it. And tap water. Because your spots are a lack of irons and calcium and magnesium are.... Good luck bro

Calcium deficiency. Add/increase your supplemental feeding with a cal/mag additive.

Hey Growmie, that’s a Phosphorus deficiency. When the plant starts to flower the demand for phosphorus and potassium increase. It will start in the lower older growth and make its way up the plant killing as it goes. Hit them with a dose of flower nutes high in P and K and you’ll be back on track! ❤️🇨🇦👊🔥

It is not normal for your leaves to be yellow in early flower, people say it’s ok at the end of flower, I guess a couple of yellow fan leaves isn’t a big deal but I wouldn’t smoke their yellow crispy sugar leaves in my bud. Some calmag will definitely help and always ph the water

Please start a diary - the more information we have about what you are doing with your grow, the better we will be able to help you. This is a calcium deficiency but just adding calmag may not solve the problem... don't know what nutes you're giving in what amounts... this could be the result of a PH that's not in the right range... in other words, you could be giving the plant everything she needs but if the PH is off, she won't be able to absorb it. PH needs to be between 6.2 and 6.5 if you're growing in soil - it's different if you're growing hydroponically.. If the new leaves are ok, then I think the problem has resolved itself but if you see more of this happening, you've still got the problem. Start a diary. Join the community... we WANT to help but this is like going to the doctor and saying "last week I had a rash, it's gone now, but what was it?" Good luck

pH watering and add more cal-mag. Goodluck with your grow buddy💚🌱