stains

Hey guys so my forbidden runtz auto is on day 41 now but ive notice today theres a weird stain on 2 of the leaves. Doesnt look like a deficiency im able to recognise any suggestions to what it is?

Hello there! I planted two seeds (Minigun by Seedsman) and one of them started showing some signs of slow growth and stains. After reading some info, I thought it could be Magnesium or Sulphur deficiency, but I’m not sure since it’s not recovering so well after I gave it a little dosis of Epsom...