2021 Highlander hybrid platinum.
This appeared after an oil change at Toyota. I was the only passenger (driver) I also have a car seat in the second row. Is this normal?

If I remember correctly, the warning light has two modes:

When the seat is empty or a child is in the front passenger seat, the "PASS AIRBAG OFF" light is illuminated.
When there is an adult in the front seat, the "PASS AIRBAG ON" light is illuminated.

So either one light or the other should be on while the car is turned on. The operation is on pages 46-47 of the owners manual- page 47 explains what happens when no one is in the passenger seat:

 

Both those warning lights are normal, depending on whether there is a passenger present in the front seat.

Additionally, there is a safety recall notice that came out last December regarding the Occupant Classification System (OCS) sensors in the front passenger seat.

See attached to determine if your HL falls in the suspect range. The production date is on the Certification label (on upper RH corner) attached to one of the door jambs.

 

You must have never noticed it before but one of the indicators will always be on. In your pic it's indicating it's off since nobody is in the passenger seat. If someone was, the the other indicator would be on.

 

The 2 is normal.