Existing debt is currently handled in a debt queue structure. If you ignore a suggestion once it will remember that and store it in that queue so that it doesn't bring it up again. There is a mechanism to review that queue but I haven't totally thought out how to resurface those in a convenient manner.
There are obvious solutions like dumping those ignored changes to Jira issues so you have a pipeline of debt to address though I feel like this just moves the issue so I'm trying to think of something more proactive.