Ayuda: Double cookies auto

Too much N will eventually cause newer leaves to get burnt tips. As you have transitioned to flower, she requires less N so residuals in the soil can burn her. A lack of micronutrients can also cause this. Micro lockout is fairly common at this stage if you're using a bloom booster because excess P and K makes micronutrients unavailable to the plant. This is also common with wind burn. Your plant shot up a lot in the last week or two and now you have a fan blowing directly on them. Easy to figure out if the only leaves really affected are those getting direct wind from the fan. Good luck, I know it's a lot of possibilities, but you should be able to figure out which is most likely for your grow!