Lack of magnesium?

If you look closer you can see its pattern. These spots appear only between vein. That's why I dont think It's from pest or fungus.

Looks alot like leaf septoria?

Thanks for advice but Im pretty sure It's not bite mark. these spots appear only on particular lower leaves which means this is some kind of deficiency.

humm i would get a magnifier glass and look under the leaves,,,, iam thinkiing for bitemarks,,, or do you have more picturees of the hole pplant ... the area that looks lkie thhis?....

Hey mate! I think it’s a lot bigger problem. I think you have spider mites in your garden. One of my plants is infested a bit but now looking much worse. You are luckier because you’re not too late. You can use alcohol mixed with water in a pump sprayer( 1 part alcohol 9 part water. Spray the plant well when lights are off and mostly the underside of the leaves and you can wipe the leaves also with a paper towel after a while. Repest it every 3 days for 10 days. Anyway they can be very challenging. Sorry for my bad english. So my opinion is you got spider mites, but we will see what others say.