Google Drive File Stream keeps enabling it's Finder extension
Google Drive Stream is defaulted to automatically start at login within the Google Drive Stream preferences.  

There are two places it can be set - system (host) wide, or user only.  The locations are as follows:


System Wide: /Library/Preferences/com.google.drivefs.settings
User Only:  ~/Library/Preferences/com.google.drivefs.settings


Check to see settings by using the defaults command to get the AutoStartOnLogin setting.  For example, to see the setting system wide issue the command:

$ sudo defaults read /Library/Preferences/com.google.drivefs.settings AutoStartOnLogin


Do this for both locations by changing the path to the .settings file as described above.

If either come back "true", you've found the cause.  Next, write a new value to turn it off.  System wide example:

$ sudo defaults write /Library/Preferences/com.google.drivefs.settings AutoStartOnLogin -bool false