Victor Jumpstart with duration increases doesn't increase the healing over time

[Dawn Priest]

Although duration increase items make the jumpstart buff last longer, the healing doesn't accommodate to it like shown in the screenshot.

 

[steventheeven3]

That sucks but that might be intentional. Since the regen is a "total" regen over 4 seconds instead of regen per sec.
They could change it to be regen per sec that gets modified by duration, but that's more in the feedback realm than a bug.