It could have been an interruption in connectivity with the registry operator(s) for those TLDs. When that happens, most registrars will at least attempt to buy domains they're currently unable to retrieve the status of. You only get charged if the domain actually ends up being created.
I have experienced this bug in Google Domains before (for non Google related domain names). Interestingly, it seems to particularly affect domains that are registered but unused.
This isn't isolated to Google Domains, however. GoDaddy's website let me go through the entire checkout process with 2 or 3 registered domain names, followed by a refund an hour later.
It must have been a bug in Google Domains, all three domains were registered ~5 years ago.