Lower leaves yellowing and curling down

Ich würde sagen, die Wurzeln deiner Pflanze haben Probleme, ich würde sagen dein ph wert ist nicht optimal, sodass die Wurzeln keine Nährstoffe aufnehmen kann. Auch, kann die Pappe in der Erde schimmeln, das gibt auch solche Probleme. Wenn du dein ph nicht in den Griff bekommst, wird sie sterben.

And yet, it also still kinda looks like overwatering... I dunno. Oh and when I said "replace" the plant, I meant, like taking it out of the soil, maybe rinsing the roots and placing it back in the remixed soil. But hey, that's like, pretty drastic.

Or a pocket of like, too acidic shit near roots. Tbh, I'd lay of nutes (if you're using), mix the soil a bit again and replace the plant, while adding some calmag and citric acid. Cheers, gl. *Sorry, referenced the element with opposite sort of effect. Looking at that again, most likely culprits are nitrogen, potassium, magnesium, iron, molybdenum. Try some molasses? (though I dunno about the molybdenum in molasses).

It can't be nitrogen at this stage and with this substrate (royalmix from Plagron)

Maybe (n)

I don't have pH meter but I'm quite sure this is not the problem

What is your run off ph?