I remember migrating from something else to Jira a few years ago - the guy who did the migration assured me that the old task numbers would be migrated to an ex

I remember migrating from something else to Jira a few years ago - the guy who did the migration assured me that the old task numbers would be migrated to an extra field in Jira (at my insistence - to avoid this issue). The old numbers were migrated but of course not displayed anywhere - there as invisible metadata that I assume has since been dropped when Jira was migrated to Jira cloud.