White tips on lower part leafs - Overwatering or deficiency?

Hard to tell, but I can't see anything. Maybe water spots or just dirt. If you see somethings crawling or like freckled spots, that would be a sign, but right now, there is nothing 👍

I see no white spots. Maybe its leftovers residue from water or feed after drying out ? Burned tips signs of potash or nitrogen, here you have clawed up leaves a bit too, so its nitrogen toxicity, slow down with N part in feeds. 200 ml for week looks not enough. Underwatering can cause salt build up. You need more saturation, from my runs in small pots would say you need double of that, not in one go, eveey 3 days or so 200-300 ml

In the future you can use your native language and people can use the translate button ⬇️