the problem is not big for you. don't worry. there is no deficiency in plants. on the contrary, some have a slight overdose of fertilizer. which manifests itself in whitening and then in drying of the tips of the leaves ..
As for the yellowing of foxes, during the beginning of flowering, it is normal when the very first lower leaves turn yellow. This is mainly due to the fact that they simply do not get light and they do not vip their function .. also during watering they are often given vada and they can burn a little over time .. as for purple stems: this can be caused from low temperatures or even from a chemical overdose of fertilizers .. in any case, the plants wiggle normally. do not overdo it with fertilizers .. it is better to give less than more ..