[2020] Game infinite saving

First thing to figure out is if it's related to mods/assets. To do that add the launch options -noWorkshop and -disableMods then start a new city to test. You don't have to build anything, we just need to see if it saves properly.

How To Set Launch Options

• Right-click on the game title under the Library in Steam and select Properties.
  
• Under the General tab click the Set launch options... button.
  
• Enter the launch options you wish to apply (be sure to separate each code with a space) and click OK. Should look like this:
  -noWorkshop -disableMods
• Close the game's Properties window and launch the game.