UNEXPECTED NEWS on 13.01.2022:
A few days ago I received an SMS and an e-mail, stated that "Your device has arrived in the repair center, and the repair is going to start soon." from Apple.
I checked everywhere, no more details have been found. I started believing that my device has been really found.
Today on 13.01.2022, I got a call from the manager of the Apple Store Munich.
He told me that they received my "lost" 2015 MBP today, even the battery replacement process has been done.
He called me because I stated him that I was worried due to my personal info that were left in that lost device. So today, he called me to make sure that the data were going to be wiped off at the Apple store, before they send that device to Apple for recycling.
After that I got a notification from "Find my iPhone" app, my device has been connected to the internet. Even the location was Munich, Apple store. Then in 10 minutes I lost the connection because they wiped off the computer.
Nobody knows what happened within UPS, where my computer was, why it took that much long. I tried to ask these to the manager, but even he has no idea. It seems this was a problem within UPS, because my device was delivered to the repair center on Monday in Czech Republic, and it came back today to the Munich.
Long story short, now I am feeling much more relaxed and satisfied. I am again a bit sad for my lovely device, but at least it feels better to know that it is not "lost" eventually. It had a new battery inside, which I wanted to have 1 month ago, but we proceeded with a different solution which was the replacement with a 2021 MBP 14". Now I started loving this device as well, it is an extreme computer, I know. Now the final result is that; I have a new device which I paid 480 euro for, my previously-lost device appeared surprisingly with a new battery inside (after all 6 weeks), however all of my data wiped off and that device is going to be sent to Apple for recycling. That is all, happy end ?