The activation of this (amber yellow) "warning" indicates that the hands free system has detected that the battery that permits the active key (1, fig. 62) To communicate and turn the vehicle on is almost discharged.
Note
In this case, ducati recommends replacing the battery as soon as possible as described in the paragraph "replacing the active key battery" (page 88).

Hands free key (hf) not recognised
High engine coolant temperatureRefitting the clutch master cylinder assembly
Insert the clutch master cylinder assembly (3) and the clamp (6) on the left
handlebar, so that the top mating faces
match the mark (z) on the handlebar as shown.
Couple terminal (6) to the clutch master cylinder control and fix them with
the screws (v).
Tighten the retaining screws ...
Pre-ride checks
Warning
failure to carry out these checks before riding, may
lead to motorcycle damage and injury to rider and passenger.
Before riding, perform a thorough check-up on your bike as
follows:
Fuel level in the tank
Check the fuel level in the tank. Fill tank if needed (page 140).
Engine oil le ...
On/off switch on handlebar
Introduction
The on/off switch on the handlebar is used to switch the dashboard on and
off, if a key has been detected, and start the
engine.
With the switch turned to "run off" (centre position), pushing downwards
switches the dashboard on or off (activating
the button inside the switch). ...