A reddit user who had been using an iPhone for a few months while waiting on a replacement for his Nexus 6P pointed out that when he went to his Google Drive account to check on his backup of the device it was nowhere to be found. Apparently when you back up your Android device the backup file has an expiration date. Even if you pay for Google Drive and choose to back it up there the only way to avoid the backup disappearing is to use your older device once every few months. It seems rather unintuitive to arbitrarily delete backups especially when stored on a paid service. Maybe they assume that a file older than 2 months could corrupt a device when installed on newer firmware? It doesn't really make sense to me. You can find this users full account of the situation at the link below. Has anyone else had a backup disappear?
via Reddit