Maxar's own blogpost Power and Propulsion Element: Five Questions with Maxar’s Tim Cole links to it's 1300 series platform page which says:
The SSL 1300 is the world’s most popular spacecraft platform, designed to accommodate evolutionary technology advances. It was one of the first spacecraft platforms to provide solar electric propulsion (SEP) and has been used to demonstrate next-generation technologies including Q/V-band, photonics and a payload orbital delivery system (PODS) that brings small free-flying spacecraft to GEO.
SSL's 1300 platform features a lightweight and high-strength structure, fuel-efficient attitude and station-keeping subsystems, high-efficiency and reliable solar arrays and batteries, and advanced command and control subsystems.
Business Wire's Maxar Delivers Spacecraft Bus for NASA’s Psyche Mission says:
In addition to Psyche, Maxar is also leveraging both its 1300-class platform and SEP technology for the NASA Gateway Power and Propulsion Element under the Artemis Program. The 1300-class platform has also been selected for NASA Goddard Spaceflight Center’s OSAM-1 mission and will host NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument.
Question: Psyche & others will use Maxar 1300 series platform; are these the first instances of a commercial communications satellite bus sent to deep space?
I ran across this while reading for How big of a telescope will Psyche's deep space optical communications demonstrator use out at 5 AU? since Psyche will be built on this platform. Since the quoted blurb is in past tense I don't think Psyche's optical communications demonstration is what they are referring to.