hey Frondo, yeah you're absolutely right: it's mag deficiency. two ways to get it fixed : add cal mag, otherwise dolomite lime . Check the comment below if you want to know more. Hope this helps ! 🚀
hey there, you're right about magnesium deficiency, here's a great ressource if you want to know more about fighting magnesium deficiency https://www.growweedeasy.com/magnesium-deficiency-cannabis