haeun I'm sorry to hear you're having trouble. That is a macOS specific trouble, perhaps you have enabled the Color management option in the Spine settings. Delete the user file once to reset the settings and it should be back to normal.

The path to the user folder is usually as follows:

~/Library/Application Support/Spine/

In that folder, there should be a folder called settings and a file with a name such as start-1.json. (The number may be different from yours.)

Before deleting a settings file, save a copy as a backup somewhere else. Then delete the file and restarting Spine. This should fix it.