PARACETAMOL suspension crystallization and discoloration

hello sir,
I am a production pharmacist and my question is "PARACETAMOL suspension 120mg/5ml occasionally change color to dark brown,complete viscosity change, and occasionally crystallization occures with the same formulation,same method,same material.
please discuss this topic in detail.

you should check your API supplier

did you run tests and validate your API?

i think mailard reaction (browning effect) occures in suspension of paracetamol,some help will be highly appreciated