Shifts slowly or stays in shifting mode longer than necessary. Must stop accelerating and wait a few seconds until the shifting is complete. Does something need adjusting?
Have you checked the level/condition of the transmission fluid?
Tester
Was the last trans fluid and filter change within suggestions in the owners manual?
I have had the transmission fluid changed (probably a couple years ago). And, at recent oil changes I have asked that they check the tran fluid. They said they did and reported no problems.
Next?
For your car, the transmission is entirely electronic, there’s nothing to adjust.
If the engine is tuned up and also the engine sensors are working properly, then the problem is most likely an internal transmission problem.
Not good news, but THANK YOU!
It could be worth a try at a new trans filter and fluid change, depending on how many miles since the last service.