In DataForm panel type, when labelPosition is default a tertiary Button is used as a trigger for the popover/mode. But when labelPosition is top a link Button is used. These should ideally be consistent.

I vote for using the tertiary variant. Hyperlink appearance is generally misleading here because the underlying element is a button, not a a. It's easy for users to be confused and expect link semantics and behaviors (like right-click open in new tab).