GV80 automatically slowing down quickly - no apparent reason

We've had two instances where we were driving with the Smart Cruise Control (SCC) and all of a sudden, our vehicle immediately slowed down as if I had applied the brakes.

One instance was on a freeway with no surrounding traffic, the other was on a long local street with no surrounding traffic; freeway speed was 65 - 79mph, the local street was 35mph (I know it may sound strange using the SCC at that speed, but it was a long stretch and a known speed trap area).

Both roads were in good shape with no obstructions in the roadway.

Our main concern is that if the vehicle immediately slows down without the brakes being applied (and brake lights), we could potentially get rear-ended.

I researched and it appears that it could be related to the Navigation - Smart Cruise Control - Highway Auto Speed option, but just curious if anyone else has experienced this type of issue and were able to get an explanation on why it happened?