Unable to remove default shortcut for iCloud Drive from MacOS Catalina

com.developer.finder is wrong.

com.apple.finder is more likely, but the shortcut is available in file dialogs, so may not be under the purview of the Finder.

First off, I'd try changing the shortcut to something else. Either do it in System Preferences, or try adapting your command from nil to -string "@$^~i"

(@ is Command; $ is shift, ^ is ctrl, ~ is alt.)

Next, you could try adding it to the user Global preferences.

defaults write -g NSUserKeyEquivalents -dict-add "iCloud Drive" -string "@$^~i"

However, it's equally possible that some key commands are hardwired and cannot be changed.