Cards that you delete are moved to the archive in vPlan.
Therefore they are no longer visible in your backlog or your planning board, but can still be restored. If you have accidentally deleted a card and want it back, you can find it in the Browse overview.
Note
This only applies to card that have been placed through an integration with vPlan. Are you working with vPlan tickets without an integration? Then deleted is really deleted.
When browsing, change the overview to Archived tickets by setting the filter at the top right to Archived.
You can then select and restore a card by clicking Undo.