Did you go into your vehicle settings and check if it has to be turned on? The manual says it can be turned on/off:
When the vehicle is started, both outside mirror LCA displays will briefly come on to indicate the system is operating. When the vehicle is in a forward gear, the left or right side mirror display will light up if a moving vehicle is detected in the next lane over in that blind zone or rapidly approaching that zone. If the turn signal is activated in the same direction as a detected vehicle, this display will flash as an extra warning not to change lanes.
LCA can be disabled through vehicle personalization. To view available settings from the infotainment screen, touch Settings > Vehicle > Collision/Detection Systems. If LCA is disabled by the driver, the LCA mirror displays will not light up.
I find it very surprising that there is no notification of any sort in the ‘25. I won’t be cut up about it if it doesn’t have it being so used to driving without one, but it is surprising.