For Deleted components, "Changed On" date should be date component was Deleted
After doing a major changes in an org, one can be left with a lot of deleted components to deploy. In the comparison view, they don't show up as expected. The Changed On" date isn't the date deleted. It uses the last modified date in the destination. So deleted something last week could up as last modified 2 years ago.
Ideal: Gearset would to get the Setup Audit Trail via API and display the actual deleted date of deleted components