The reason your emails are coming from "k1.send" is because your account is new. It usually takes some time for the new branded sending domain to fully take over. In the meantime, Klaviyo uses a default sending domain.

As long as your SPF, DKIM, and DMARC are passing (as shown in your screenshot), your emails should still be delivered properly.

This period acts as a warm-up for your new domain to establish a good sending reputation. To help this process, continue sending regular emails and avoid sudden spikes in volume. Over time, you'll see your branded domain being used more consistently.

In the meantime, there's nothing specific you need to do, just keep an eye on your email performance and ensure you’re following best practices for email marketing.

Hope this helps :)