The problem with k deficiency is that it does look like burn at first, I knew it was not burn as I was underfeeding from the start and that's just how I roll, unless you have access to soil testing 😂 you are at mercy of the tools you have and the signals from the plants, I was pretty sure it was deficient just had to wait until the tell tail side yellow on old growth, I bet a lot of people have had this at some point and made things worse by flushing and the like, it's all about patients and the plant will eventually show you a definite signal, hope it's helpful for anyone, I'm not stressed because I know from experience, I just get confused over the symbols p & k , that's smoking and age lol