Brown spots

2 Resources I use often 2.https://www.growweedeasy.com/cannabis-plant-problems/calcium-deficiency 2. When your cannabis plant has a calcium deficiency, the main symptom that you'll be able to notice is brown or bronze splotches or spots on your leaves. It is also often associated with yellowing (though leaves don't always turn yellow). Occasionally the splotches may appear purple especially under LEDs.

I had this on my grow. I diagnosed it to be nutrient burn so I just watered with Ph'd water for a week. All new growth has been green and healthy so far :)

Might be the light its hard to say withought knowing the light,and distance use an app like tent buddy to get your to check your par or ppfd. That will help ya quickly adjust and then move to your next trouble shooting step

Having a diary makes it easier for us to help you, but it looks like your ph may be off causing lockouts. The leaves are nice and green, so maybe not deficiency, she just can’t access the nutrients in the correct ratio. Week 4 in flower is when she starts getting very picky about everything. I would recommend checking runoff ph and doing a flush if it’s off. Then follow with a half dose of nutrients. Give her a couple of days. The damaged leaves won’t recover, you are looking for it to not get worse. Also important to double check light distance and environment at this time. Best of luck!

Looks a bit nitrogen heavy, but could also be Ph is off

This is burning from over feeding..........not a calcium deficiency. The super green leaves are the clue........waaaay too much nutrints.

è carenza di calcio basta correggerla con un po' di cal mag