I forgot to update about this earlier. We ended up finding that there was an incorrect diode installed on some Fathom-X boards shipped between May and June 2022, which “severely reduces communication bandwidth and affects the video streaming to unusable levels.”
The correct component (on the left) is labeled “5C”, while the incorrect component (on the right) is labeled “05”:
If you have an affected board you can contact support@bluerobotics.com with your order information to receive replacement boards as relevant 