Problem Definition

When moving Jira and Confluence from one cloud instance to another cloud instance ,the remote-links (in below format) present in Jira under "Mentioned in" rail still points to source Confluence.

/pages/viewpage.action?pageId=<pageid>

This impacts all migration methods via CSV/XML export/Import or via C2C migration tools

Suggested Resolution

As described in Links to Confluence Pages, it will be helpful if the Link-fixing tool supports the update for these remote-links.  

Temporary Resolution

In this case you contact Atlassian support by logging a request in support.atlassian.com and ask them to apply the workaround for this issue.