Ether turn of cloude saves for all games at...

GOG Galaxy/Settings/Game features (unchecked the box cloud saves)

...or just for CyberPunk 2077 at...

GOG Galaxy/Cyberpunk 2077/Settings/Manage installation/Configure/Features (unchecked the box for cloud saves)

...then go to...

C:\Users\*USERNAME*\AppData\Local\CD Projekt Red\Cyberpunk 2077

...and open the file...

UserSettings.json

...then you look for this section...

"name": "EnableCloudSaves",
"type": "bool",
"value": true,
"default_value": true

...and change it to this...

"name": "EnableCloudSaves",
"type": "bool",
"value": false,
"default_value": true