The goal of this clinical trial is to understand the mechanisms leading to olfactory dysfunction (OD) in chronic rhinosinusitis (CRS). The main questions it aims to answer are: * Is the type 2 inflammation impacting the olfactory epithelium regeneration, leading to OD? * Does a treatment interfering with one of the major T2 inflammatory cytokines, have an impact on the mechanisms of OD in CRS? Participants will undergo olfactory testing and nasal brushing before and after 3 months of treatment.