When i run Cyberia 2, Dosbox remains in a black screen with the white DOS cursor, i close it and i get a error message that the user storage cuota for the cloud saves of this game are exceeded, it shows that my saves are too big (hundreds of MB or even like 1GB), if i run it again with the syncing off the game runs fine.

I opened the folder where the cloud save data is, and i figured out that there is a file called "CYBERIA2" that grows larger and larger the more time i wait on the black dosbox screen i mentioned before. If i delete that file, or if i close and open gog galaxy again and try to play the game, the problem happens again.

That file is not a save file either, because the save files of this game have the name that you enter at the beginning of the game, have the ".log" extension and are like 1KB.

I cannot delete that file when the game is running, i get a error message that Dosbox is using that file.

Best to open a support ticket about this. I assume there is an issue with DOSBox overlay fs and this game or how that interacts with Galaxy. You could also try asking Qbix in the DOSBox Cloud Saves announcement in General. I don't know how often they are checking it though. They're a regular over at VOGONS, but that's assuming it's a pure DOSBox problem.

The problem still remains. SUCKS.