I don't believe so. If you look under the FAQs and the "Security and Control" heading of the Features page, there is no mention of encryption beyond AES-256. Companies offering E2E typically like to highlight that somewhere, even in a non-technical way.
Furthermore, the security is apparently "fully managed", which to me translates to "keys securely stored on our servers, not client-side."
Furthermore, the security is apparently "fully managed", which to me translates to "keys securely stored on our servers, not client-side."