hi smokesalot,
plants are around 1 month from germinating.
The pot is around 20 litre of soil, they were feeded nutes just a day ago.

Actually, the issue got worse over the night. Where you could see the light green spots is now brown. It's interesting to see that it's only the 3rd set of leaves actually experiencing this. the new ones and the older ones appear fine so far.

I'll update with pics this afternoon.

Cheers,
Carisma