Are my plants sick? Yellow leafs and dark spots

peccato, errori da principiante... andrà meglio la prossima volta. 😃

Plant looks hungry. Looks like you only used water to grow

Ask for help when the symptoms start as opposed to when the plant (3rd pic) is about to die. no diaries, but looks like the plant was fairly healthy 16 days ago... think about what you did and don't do those things next time.

Pics 1 and 2, calcium deficiency. Pic 3, all sorts of issues. Too late to fix anything before harvest. Without a diary and/or a lot more information, it is hard to give specific advice without knowing what you may be or may not be doing.

The younger plant looks like it has Manganese deficiency. I wouldn't go crazy and try to fix this at this stage. Your plant is not far from being done, so a tiny dose to not let it get worse is the most I'd do. The older plant looks like it's just about done and while you might have some deficiency on her too, it is too late to do anything about it. It looks like she's foxtailing a lot, which is not a problem, besides deciding when to harvest as you now have young bits of flower and old bits on the same plant. Judge the ripeness on the majority, but just let her finish. You now know that plants like to eat a lot when they bulk up in flower, so next grow just anticipate it and give it more food as you switch to flower.

They just seem to be asking for nutrients, Calmag/N-P-K Nitrogen/Phosphorus/Potassium, are you using nutrients? Check deficiency charts on google they're quite helpful. For the plant closer to harvest i would keep in mind that you might want to flush/feed only pH'ed water and let her use the nutrients left in the soil. Also she could be naturally turning darker (autumn colours), to a certain extent of course. Happy growing mate🌱