cURL error 28

Users attempting to register are suddenly getting this error:

email validation failed. cURL error 28: Operation timed out after 45001 milliseconds with 0 bytes received

The plugin has been working fine for years up until now.

I also noticed there is a NEW tab called Email Validation in the plugin settings. If I attempt to validate an email address using the provided tool, the console reports this:

users.php:1 Access to fetch at ‘https://isspammy.com/wp-json/email-validation/v2/validate_email’ from origin ‘https://mydomain.com.au’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: The ‘Access-Control-Allow-Origin’ header has a value ‘https://app.isspammy.com’ that is not equal to the supplied origin. Have the server send the header with a valid value.
EmailValidation.js:181

POST https://isspammy.com/wp-json/email-validation/v2/validate_email net::ERR_FAILED

validateEmail @ EmailValidation.js:181
onClick @ EmailValidation.js:512
Xa @ react-dom.min.js?ver=18.3.1.1:10
B @ react-dom.min.js?ver=18.3.1.1:10
W @ react-dom.min.js?ver=18.3.1.1:10
qe @ react-dom.min.js?ver=18.3.1.1:10
Ke @ react-dom.min.js?ver=18.3.1.1:10
(anonymous) @ react-dom.min.js?ver=18.3.1.1:10
dl @ react-dom.min.js?ver=18.3.1.1:10
V @ react-dom.min.js?ver=18.3.1.1:10
Je @ react-dom.min.js?ver=18.3.1.1:10
pe @ react-dom.min.js?ver=18.3.1.1:10
fe @ react-dom.min.js?ver=18.3.1.1:10

If I disable the Validated Emails On Register setting, it works fine. But obviously I’d rather have that setting enabled.

I initially thought I’d hit the free tier 50 daily validation limit with Ispammy, but l checked and have only used 25 / 50 credits in the past 7 days.

Note: I’ve changed my domain in the log above for privacy reasons. Otherwise the log is exact as reported.