@Kimmyann253 the yellowing is actually from nitrogen deficiency. You can feed with nitrogen/grow nutes up to week 3/4 of flower then cut it out and just use your pk nutes starting with higher phosphorus then lower phosphorus and increase potassium a little until mid flower then you start decreasing feeding to 3/4, 1/2, and then 1/4 for the last feeding before harvest.
It will keep the foliage healthy and green until the flower fade starts to happen mid flower and then you’ll start getting a nice golden fade with orange and purple hues depending on strain.