I am working on a car that wouldn't start and where the key was stuck in the ignition cylinder.
[More on that project later, but I noticed something strange that my 03 Q45 doesn't do.]

I accessed the key cylinder and released the key. Good!
The battery is decently charged, and will crank up the car.
I did the following tests with the headlight switch in the OFF or AUTO position, with the same results.

• Open front left door (driver US) and the parking lights flicker on, stay lit momentarily and then turn off.
• Open any of the other 3 doors and the parking lights stay on until that individual door is shut.

Lock/unlock the car manually or with the fob and it behaves the same.

Now, I see a benefit in this system being a door reminder system, but I don't see why only one door should behave any differently.
I saw nothing about this is the owner's manual, but maybe I missed it? I have a feeling this is the car warning me of some module not getting power... maybe related to why it cranks but won't start.

What do you guys think; does anyone else's Q45 do that?

Definitely one of those warning signs I suspected.

There was a blown fuse. I replaced it and order was fully restored in my little universe.
The lights now behave normally and as a big prize bonus, I have solved the no-start/key stuck in ignition issue.

This reminds me of one time the fuse for my interior lights (dome lights, step lamps) of my 2003 M45 were blown. The self-closing trunk refused to work. It definitely caught my attention and I traced the issue to bad fuse. Its interesting as to how these cars were made.
Outstanding build quality.