In MDEV-31039 "backup_fix_ddl()" function was moved in "CorruptedPages" class. The class was created for the specific case, when we have non-zeroed unallocated InnoDB pages, what was treated as error, and we did not find the reason of such pages existence, that's why we decided to create some crunch in mariabackup to ignore such pages to let users to restore backup with such pages(see MDEV-22929). But "backup_fix_ddl()" function creates ".ren" and ".del" files, which are processed on "--prepare" stage to handle removed and renamed during backup files. It does not have any relation to CorruptedPages class at all.