This is what will happen to all grounded aircraft. Without a fresh airflow, the cabin will quickly become a breeding ground for mould and other fungi to rapidly breed and spread, permanently damaging leather and fabrics. The only way to efficiently prevent this happening is to set up regular fogging in cabins using a long term disinfectant. Standard disinfectants will need more regular fogging resulting in higher costs.
Bacoban for Aerospace once applied provides 10 days protection. Standard disinfectants provide only one-day protection.