Weird light green/ brown blotches

Can someone help tell me what could be going on this is starting on some of the lower leaves of my 3 week old plants.

Quick update- I have noticed today that some of the plants are showing signs of nitrogen toxicity with some slight leaf curl at the tips. Could this discoloration be related to that ? I’ve dealt with nitrogen toxicity before but never seen that discoloration on the leaves.

Have you looked closely under the leaves?

Yes I have. No sign of bugs if that’s what you are saying. If it was a bug what kind would make this kind of damage ?

Here, looked like the calcium one to me. pls do make your own decision on it though.

Thanks for that. Yeah it could be cal mag. This is what the leaves look like after a couple days. I’m not worried if it’s some sort of deficiency, I’ll get it figured out. Just worried about potential bugs, there are none as far as I can see unless I’m missing them, and I have sprayed in case. Does any bug make this kind of damage.