Very good backpack.
I found it at a very good price, around fifty euros from Kotsovolos!
It has a single space as I wanted, so I can use it for everyday use too!

It is slightly smaller than a school bag, but it doesn't lack space. The fabric is durable on the outside and soft on the inside. Although it is not waterproof, it can withstand unexpected rain if you don't take an umbrella.
The cable for the power bank passthrough is a smart solution for hanging cables, and it works exactly as it should. The hidden compartment on the back is necessary for traveling abroad, it fit wallets/passports/tickets and there was still space left. Ideally, I would like a bit more division or extra pockets inside (it only has one internal pocket with a zipper), but there is no reason not to get it.
Recommendation for motorcycle friends, the card holder on the shoulder strap is great for tolls, you don't have to deal with pockets and chaos.

Edit -7/2024:
Within 3 months, the plastic lock of the zipper broke and doesn't work, fortunately, the compartment still closes.