Taskade lets you quickly copy and move tasks from one project to another. You can also copy/move tasks between workspaces and folders. There are two ways to do that.
(···) Three Dots Menu
Click the (···) button to the right of a task.
Select 📋 Copy To or ➡️ Move To.
Choose a Workspace/Folder and pick the target Project.
Drag & Drop
Left-click and hold the the drag button ⋮⋮ to the left of a task.
Drag the task to a different project in the sidebar on the left.