Hi and a good morning from Austria,

you are right, this is indeed quite late to the party, and I really had to read my email notification twice. Thank you for your reply nevertheless.
However, I am afraid, that the problem simply was with a corrupt devboard. I got a new one, flashed the same code ...

For anyone wondering, the device itself was defect. Ordering a new one and flashing the exact same code fixed it.

Hardware:
Board: ESP32 DevKit V1
Core Installation version: 1.0.4 (Board Manager ESP32 by Espressif Systems)
IDE name: Arduino 1.8.12
Flash Frequency: 80MHz
PSRAM enabled: No
Upload Speed: 921600
Computer OS: Windows 10 1909

My Problem
I tried to get a bit into the deep sleep states of the ...

Hardware:
[]Board: ESP32 DevKit V1
Core Installation version: 1.0.4 (Board Manager ESP32 by Espressif Systems)
IDE name: Arduino 1.8.12
Flash Frequency: 80MHz
PSRAM enabled: No
Upload Speed: 921600
Computer OS: Windows 10 1909

Description :
I tried to get a bit into the deep sleep states ...