I’m not certain if blank redirects will cause this.
Troubleshooting these payment gateway issues is so difficult, since I cannot actually test or see your Stripe details– nor would I be able to check anything outside of your client ID and keys anyway.
Are you testing with a separate vendor account? In other words, are you using a different Stripe account for the test vendor on your site? You cannot also use the same Stripe account as you are using for admin..
I’d also encourage you to ask Stripe and see if they have any insight, as they may be able to see more on their end of the transaction process and what you’d receive an error from keys that you do not even have on your site.