The most common cause for this is caching. When your pages with payment buttons are cached, the security keys used on it will be stale. Do you use any caching plugin? Does your hosting provider used forced caching on your page?
Stripe payment plugins for your WordPress site
The most common cause for this is caching. When your pages with payment buttons are cached, the security keys used on it will be stale. Do you use any caching plugin? Does your hosting provider used forced caching on your page?