Update: 9.11.2021 - We have updated this article since it's weird :D
We had a long outage earlier today, and I want to explain everything that happened. The power outage was affected my whole city.
Basically, I was just chilling, and suddenly our power went down. Power surge protection kicks on my PC and a loud click sound came, as well as my server and router went down. Our electricity company hasn't made an update for it.
The power was down for a second, but it may have corrupted my server's disk drive. My server never showed a sign of getting back online and stable, and I considered that the server was never getting online. It may have been an unsuccessful restart of SSH, but who knows?
What do we learn from this?
I've been thinking of getting a PSU for my Raspberry, so nothing like this wouldn't happen. We learned that it's important to have such a thing. Everything would have been recovered faster, but Debian didn't like the unexpected shutdown, so I had to change to Ubuntu which took time.