What is the need for an Immutable Ledger?
Immutable Ledger In ERPNext
https://docs.erpnext.com/docs/v12/user/manual/en/accounts/articles/immutable-ledger-in-erpnext
Freeze Stock Entries
https://docs.erpnext.com/docs/v13/user/manual/en/stock/stock-settings#12-freeze-stock-entries