Hey @Persona! Double opt-in is an industry standard which is why it’s applied automatically within Klaviyo. It prevents bots from subscribing to your list and ensures only real humans who want to hear from you are subscribed. So, having a lower number of subscribers than form submissions means it’s working!
Unfortunately, since the profiles who did not confirm their subscription have not consented to hear from you, you should not target them a second time -- especially with SMS. You’ll risk your deliverability with an increase of spam complaints. The best thing from this point forward is just to stick with single opt-in, though I definitely don’t recommend that!
Hope that helps :)