I haven't used the product but if the key is in the fragment segment of the URL then its not sent to the server. This is a pretty common pattern for these e2e encrypted web apps.
> The fragment of a URI is the last part of the URI, starting with the # character. It is used to identify a specific part of the resource, such as a section of a document or a position in a video. The fragment is not sent to the server when the URI is requested, but it is processed by the client (such as the browser) after the resource is retrieved.
> The fragment of a URI is the last part of the URI, starting with the # character. It is used to identify a specific part of the resource, such as a section of a document or a position in a video. The fragment is not sent to the server when the URI is requested, but it is processed by the client (such as the browser) after the resource is retrieved.
https://developer.mozilla.org/en-US/docs/Web/URI/Reference/F...