Yesterday the plant did not have those spots, even the leaves became greener

Those spots on the leaves could be caused by a few different issues Here’s what I suspect based on the photo you sent 1. Possible Calcium Deficiency (Most Likely) Symptoms: Rusty brown spots, usually appearing on older leaves first. Cause: Common in coco and soil grows if Cal-Mag is lacking. Fix: Add Cal-Mag (around 0.3-0.5 EC) to your feeding routine. Make sure pH is 6.0-6.5 for soil. 2. Nutrient Burn (Mild) Symptoms: Slight yellowing/browning at the edges, not widespread. Cause: Too much fertilizer, especially with high nitrogen or potassium. Fix: If you’ve been feeding heavily, flush with pH-balanced water and adjust EC but I don't think that's the cause here. 3. Pest Damage ( very Less Likely) Symptoms: Irregular spots, possible tiny bite marks or discoloration. Check and Look under leaves for mites or thrips. Fix: If you see pests, use neem oil or insecticidal soap. 4. Light Burn or pH Fluctuations If the plant is too close to a strong light, spots can appear. If pH swings too much, nutrient uptake is blocked, leading to deficiencies. What to Do Now? Check pH and EC. Make sure pH is within 6.0-6.5 for soil. Add Cal-Mag if you’re not already using it. Monitor new growth. If the problem stops spreading, you’ve fixed it! Let me know what nutrients you’re using and if you’ve noticed any pests! I bet on cal mag in your case tho. Happy growing! She looks healthy besides that, can't wait to see the harvest!.

Does not look like ca Ca or Mg issues to me. Looks like a swing in PH causing some stress. The markings on Ca are burning, random and circular like, the issues with Mg are more chlorosis between the veins and they improve on feeding it Mg. If it was light based I would think the top leaves would be a bit burnt or weird looking and they are mostly ok. Might be a bit yellowish but that should green up in no time. I'd look at what you feed them and when you watered them last. If you did this recently I would say that is the cause of it.

How close is your light? to me this looks like light burn. The plant is very short this is why i guess but would be nice to know what you feed, how and just in general more info.

Hey there! I‘d check for pests, also make sure to Look on the bottom of the leaves. Also it could be a CalMag Issue. Good luck with figuring out the sorce of this problem!