google-drive-file-stream has 39 questions. According to its tag wiki this tag should be used for the Google Drive clients launched in 2017 and the current client.
google-drive has 538 questions. According to its tag wiki, this tag should be used for the Google Drive client that was discontinued in 2017. [google-drive] created:2017..2023 is:question returns 256 questions posted since 2017 with this tag which are very unlikely that a high percentage of them be about the discontinued client. Most of the new questions related to Google Drive use this tag instead of the mentioned above.
If the clean-up might not be worthy, then I think that
google-drive-file-system should be a synonym of
google-drive. What do you think?
google-backup-and-sync has 28 questions. It hasn't tag wiki. According to the tag wiki of google-drive-file-stream, the google-backup-and-sync should be a synonym of google-drive-file-stream.
Additionaly to the above, another situation tag used sometimes togheter with the tags mentined above is the following:
google-sync has 65 questions. It hasn't tag wiki. According to What is Google Sync
Google Sync uses Microsoft Exchange ActiveSync 12.1 to let users synchronize their work or school mail, contacts, and calendars to their mobile devices.
google-sync is used on some questions about Google Drive, some of them together with google-drive, google-backup-and-sync, google-photos, google-chrome, among other usually unrelated tags, which doesn't match with the above description of Google Sync.
Some of expected tags to be used in questions related to Google Sync are microsoft-outlook, apple-mail, exchange, calendar and similar tags.
NOTE: Google recomments organizations to stop using Google Sync in favor of other more secure options as it doesn't support OAuth2 (the source of this is the previous link).
It might be needed to add a tag wiki to google-sync and do some retag / clean-up.