Dog diagnosed with blood parasite and suddenly won’t eat kibble… has anyone experienced this?

My 11-year-old Labrador suddenly stopped eating his Happy Dog kibble a few months ago. This is the same kibble he had been eating happily for the last 4-5 years.
The crazy thing is, this dog used to CRY for his kibble. He would beg for it and even eat it if I dropped some on the floor. Until one day he just stopped!

Now he sniffs it and walks away. I’ve tried so many different kibbles over the months royal canin, purina pro plan, Farmina. this dog is making me broke :(
I finally took him to the vet and found out he has a blood parasite that caused mild anemia and low platelets. He’s now on treatment.
The weird thing is he eats everything else, JUST not kibble. My vet told me to feed him whatever he wants right now because he needs to eat and recover, so I’ve been giving him boiled chicken, rice.Which I know lacks that balanced nutrition but he just needs to eat right now!!

Has anyone experienced their dog suddenly hating their favorite food after getting sick? Did they ever go back to eating it after recovery?