Polo 9N automatically locks itself

Hello, I have the following issue with my Polo 9n 1.4 TDI Comfortline, manufactured in 2002:
Problem with the central locking system:

After the engine starts, the vehicle automatically locks after a few seconds.
A few seconds later, the alarm system goes off, even though the engine is running.

At the same time, the following errors exist:
- The turn signals no longer flash when opening or closing with the key fob.
- The entry light under the door no longer turns on when the driver's door is opened; only the interior lights come on.
- The tailgate no longer connects with the front door at all.

The only way to stop the alarm system from activating is to briefly press the "open" button on the central locking module after starting the engine, then lock the doors in "auto" mode and immediately unlock them again.

I am familiar with the document titled "Doku Polo MJ 2002, doors lock automatically."
Some of my problems are being addressed there.

Are the other problems also a consequence of the defective capacitor in the door control unit?

PS: All the fuses are okay, and my dealer is at a loss!

Regards,
Sure, here is the translation of the text from German to English:

"Thank you."

Microswitch on the driver's side door is defective.
Your car doesn't detect when someone gets in. This behavior is normal. If you feel like it and have the time, you can try to repair it yourself (I did this on my Golf; I found instructions online, but I need to find them again. You should be able to find them on Google).
Alternatively, you could buy a new lock cylinder. However, that's quite expensive; I recall it costing around €200 for the Golf, compared to about €1 for the microswitch. The microswitch is located in such an awkward position that the lever pressing on it doesn't hit it axially, which gradually destroys the switch over time.

Does that mean there are two electrical contacts?

Because the interior vehicle lighting reliably turns on when you open either the driver's or passenger door!

Only the door entry lights located at the bottom of the door remain dark after being opened.
the driver's or passenger door, and of course, the other problems mentioned...

Regards,
Sure, here is the translation of the text from German to English:

"Thank you."

As far as I know, there are actually four microswitches in the lock. Please search on Google; I think the Polo has the same type of lock.