Some leaves starting to die / first day of 6th week of flower / Potassium deficiency?

NPK def Uw bb

Most of the time it's environmental which leads to problem which can present as nutrient. Curled down almost clawed leaf is clear signs of overwatering, or water is sitting in out too long of a time. K def would not present so sparingly, the tips dying off from outside in tells you it's controlled by the plant ( deciding what to sacrifice first based on priority ) Waterlogged soils with lack of oxygen can often messes up iron and how it converts in a medium causing problems. Worth checking your ph make sure she is has not drifted alkaline. Which will also mess with iron. Just a guess based on visual. Hope you get it sorted. I'd lean towards iron chlorosis but wait n see what other think.

You should aim for the faid at the end of the flowering Stage ( last 2 Weeks ) but for now it looks a Little Bit to early…