When copying or analyzing the copy of a list item or document, Sharegate displays the following error messages:

This error occurs when a list or a document library has a self-lookup field and the item copied or analyzed refers to an item that somehow refers back to the item.

You could simply migrate the item again using a custom template with Version history unchecked. If the item is copied again with the version history, other items referencing it at the destination will lose their lookup value. Otherwise, you could manually update the value in SharePoint. Unfortunately, the item won't be copied when the lookup value is required. When this is the case, the item could be copied again without the version, or you can change the field so that it isn't required.