N.B. note that Google performs some encoding conversions within the GMail backup from Takeout that permanently break all non-ascii characters when an encoding other than UTF-8 is used in the original mail (those characters are replaced by the 0xEFBFBD sequence, and since information in lost it guess it cannot be properly recovered).

Obviously I am not the only one who have been experiencing the issue, e.g. https://webapps.stackexchange.com/questions/71153/takeout-br...

The issue does not happen when doing backup with another tool e.g. mbsync.

As it stands, Google Takeout is not sufficient. While attempting to export data, you can still get a "sensitive action blocked" and "we can't verify it's really you"-style errors that indefinitely prevent access to that data. I've encountered this myself when trying to export my YouTube subscriptions, and it gave me pause when I considered that this could happen to more serious data. It's not a one-time issue, either, I've been retrying export for months now without success.

The responses I've seen to other people with this problem are not encouraging, amounting to "oh, you must have done something out of the ordinary, try again in a few days". See, for example:

https://news.ycombinator.com/item?id=20054083

https://old.reddit.com/r/DataHoarder/comments/i6cn1x/google_...

https://support.google.com/accounts/thread/13380514/i-can%E2...

https://twitter.com/veerismo/status/1341605248834498561

Edit: better links

Is there a good way to automate this?

I hope you checked your data and tried to restore everything. I pulled out my Google Music data about 6 months ago and it was almost unusable with Google mixing all the data in one folder.

where do you backup the data? I keep it in the Dropbox for now (anything other than GDrive)