WhatsApp may not be able to use unlimited storage space for backups to Google Drive in the future. WABetaInfo found references to such a limit hidden in a beta version of the app.
A few months ago, WABetaInfo found references to options not to upload certain parts of chat backups to Google Drive to save space and was already feeling wet. As of 2018, WhatsApp backups to Google Drive do not count against the maximum storage space in the cloud. Now there are concrete references found to a ceiling of storage space for these backups.
WABetaInfo posts a handful of text lines on its website such as ‘Google Drive backup changing’ and ‘Google Drive limit reached’. The site concludes that “a certain quota of storage will still be free, but limited.” Such texts are of course not the equivalent of an announcement from Google or WhatsApp, but the rules do come from WhatsApp itself. It is not known when the limits could apply.
On the Apple side, the situation has always been this way: WhatsApp backups on iOS to iCloud simply count as used cloud storage space. WhatsApp also offers the option to create a manual backup and store it on the device, but an automatic backup to another cloud destination is not an option.