I've been using Google Drive to backup via Time Machine on a macOS 10.13.6. More precisely, I've created a sparse bundle disk image, attached such image and mounted it in order to make it visible to Time Machine.

Now, usually Time Machine finishes the backup way before Google Drive completes syncing all the files. Occasionally, however, either my computer sleeps or due to other reasons my internet disconnects. Or, maybe worse, due to power outages, my computer might eventually turn off. In those cases, what happens to whatever is being written inside the disk image?

Usually, when the internet disconnects and reconnects again (even after several hours), Google Drive seems to indicate that the progress could be resumed. At least, I see some files similar to the ones when Time Machine output was being uploaded. However, I'm unaware on whether some of these files were corrupted or, even, whether all the written files were uploaded.

So, in summary, after creating a file inside the Google Drive folder, for how long and how much can Google drive stores the files locally before uploading then with and without internet connection?

Extra questions. How are the locally cached files stored (both online and offline) and how can I explicitly see them?

Thanks in advance.