Engine Revving

While your situation might change, currently that's normal and simply means your car is having a losing streak in driving conditions for fuel efficiency, which is perfectly normal as long as it stops happening after driving conditions have changed.

 

When this happens, look at the dash display, see if the battery meter has dropped a few bars.
If so, then it is the engine charging up the high voltage battery.
This may occur after starting up and driving right away. The drive will
use battery power for the most/all part until the engine goes thru its warm up stages.
Moreso after the HV battery ages.

Has it been properly maintained?
Might want to check your 12v aux battery for resting voltage or load test. Age?
Might want to check your air filter under the hood, just in case.
Might as well check your oil dipstick to be safe too, if the service has maybe forgot a few things?
Who is doing the regular service?

How many miles? Are you original owner?

 

I think this is the most likely answer. And it is more likely to happen if the A/C is going full blast.

OTOH, if your HV battery starts spending most of it's life with the charge in the lower half of the range.......it might be an early sign of a failing HV battery.

Just keep an eye on it for a bit.