It would be very helpful if a task could be converted to a backlog item.

Use cases:

While testing a backlog item you find an error and report it as defect task.
Then it gets clear that this defect

1. needs to be fixed by another team/module
2. is too much effort/too unclear yet to be fixed now and needs to become a separate user story

In both cases you currently have to create a new issue (1.) or story (2.) and manage to transfer all the description, screenshots, attachments, comments manually to this new item. And finally somehow link those two items and close the original task.

To avoid the need to create the item twice, you currently have to store all your information somewhere else until you clarified what needs to be done.
This blocks the flow of daily work. Especially if the one who could investigate and decide is not available due to vacation or being busy with other work.

It would be much easier if you could create a task for the defect you found and could convert this task later to any type of backlog item that seems appropriate.

Also the opposite way of conversion might be helpful: someone finds a bug and it gets clear that this has been caused by an implementation of a backlog item - the you would like to convert the issue to a defect task.

But the direction task -> backlog item is more important!