It is difficult to make the splice waterproof, especially the connector to the drone. If the tether takes in more water, data transfer rate gets disrupted. By using the original connector on the drone side, Blueye Pioneer underwater drone will not take in water while it will try to splice and a user can dive with it while waiting for a new tether.
Warranty will be lost if the tether causes a problem for other parts.
Read more here: Changing the tether