Until JSWSERVER-20910 is introduced, our customers could use a healthcheck warning thrown when there are more than one Rank field in the instance.
Third-party tools can import multiple Rank fields which can have havoc over indexing performance. Introduction of a new rank field might go unnoticed by administrators as this is not a visible field on the issue view. So administrators might not be aware of this newly introduced Rank field until it's too late.
A Jira healthcheck warning can proactively let the admins know that they have multiple Rank fields and this can potentially impact indexing performance.
A "Fix" button should check if the non-default Rank field(s) is/are being used in any of the filters and if not delete the Rank field.
Manually check if there are more than 1 Rank field in the Lexorank Management page on the Jira UI (esp. after a project import) and if you see more than one Rank field, follow this kb to Manually Remove duplicate Rank fields in Jira server
Keep in mind deleting the Rank field doesn't delete the Rank data from the AO_60DB71_LEXORANK table. Ref: JSWSERVER-13098: JIRA Agile doesn't delete rank from table when the Custom Field was deleted