Rust Fungi or Deficiency??

It is my first time growing. I’m growing outdoor in a cold frame and the plant we’re doing great for the first few weeks growing at an accelerated rate. One day I started noticing some small rusty, brownish, but also kinda shiny spots. I’ve been reading a lot about cal mag deficiency and also about rust fungus. Some of the plants are turning pale/yellowish at the base of the stem. I’m not sure what I got going on here and was looking for an experienced eye. Thanks for any help.

Growing because you want to “ experiment “ can introduce problems ... like your overwatering .

Here is some of the issues I see ....

1. You are overwatering the medium ( soil )
2. You are using “ half filled “ cups ... plant will exhaust Nutes from that quickly
3. Clear cups ... light on exposed roots .
4. Cal mag issues .... From shallow soil ( deficiency of available Nutes ) , or losing ph from it already.

Why not just plant them under normal circumstances.... cannabis can weather certain conditions, but just curious on reason to
“ experiment “ vs . Growing for a harvest.

Thank you that’s a lot I had not considered. I just found the seeds in some of my bud and decided to grow and trust me I’m growing to harvest. I’m just such a noob and didn’t know if it would work.