Hello ! If it was a phosphorous deficiency then your leaves would not yellowing like that. In your case I think that your plant are suffering from serval deficiencies. Your leaves are yellowing because of a nitrogen and a potassium def and mayby some trace elements like Zinc . If you have 5 weeks to fix his then increase a bit your fertilizer amount , at that stage you'r already using a bloom nut that will provide enough N for the end of the grow and enough PK to help the buds to get fatter and taste better . I hope it will help you 😁👍