Comment 28 for bug 1747646

I have prepared a new beta release of deja-dup that might fix this issue. The 39.x series has switched from GNOME's Google keys to our own keys and from the GIO duplicity backend to the pydrive one. Which may alleviate some of these issues (on the presumption that part of it is that the GNOME key's quotas are being hit or how GIO is re-authorizing).

To test if the new 39.1 release helps, you can run:
snap install deja-dup --classic --beta

Or if you already had the snap installed:
snap refresh deja-dup --beta

When you next back up, you will be prompted to re-authorize deja-dup to access your Google account (with vastly diminished access than the GNOME keys, which is nice).

I will optimistically close the deja-dup side of this ticket. Please re-open and comment if the above release does not help matters.