What nutrient problem is this?

I looked at the deficiency chart with the pictures and thought it was a phosphorus problem but now I think it is a manganese or potassium problem.

Can anyone tell me whats going on? Its slowly starting to happen with my other plants.
And if there is anything common in a household I could use to fix this plz lmk

Looks like calcium,how about giving us some info?

just going to jump out on a limb here and ask if you are using r/o or distilled water,lol

Usually at that age the problems are due to over/under watering, or overfeeding (usually from the soil being too hot.).

Your soil looks heavy/dense. I would add 50% perlite next time. (I'm crazy for perlite. I think it's God's gift to cannabis.).

What soil are you using?

looks like I got a dingleberry, how do I get this turd off my ass?