What is this from?

Either pH is off or

does seem reminiscent of Calcium deficiency. It will not get better but it should stop once treated. Check you PH as well. might be available but not in range. https://420life.com/wp-content/uploads/2021/10/Marijuana-Leaf-Deficiency-Chart-scaled.jpg Use this chart for leaf systems to help narrow it down.

It’s either Cannabis leaf septoria or calcium deficiency. I would remove damaged leaves and try adding calmag when feeding. I would also try to reduce the humidity in the grow room, improve airflow. Also maybe a bit of defoliation: you could remove those leaves that were also touching the ones suspected of fungal infection

That looks like either a burn from getting some nutrient water on the leaf or bug bites.