Selling The OC season 2 heavily Brett Oppenheim, who owns the Oppenheim Group with his twin Jason Oppenheim, which confused many after his absence on Selling Sunset season 6. Throughout Selling Sunset season 6, many were wondering where Brett and Jason were as the season continued on and many of their responsibilities to Mary Fitzgerald. While Jason seemed less present on Selling Sunset season 6 due to his relationship with Mary Lou Turk, Brett's absence was less explained. When he showed up on Selling The OC season 2, many were confused about why he was so much more present on the series.
https://screenrant.com/why-brett-oppenheim-on-selling-oc-season-2-not-selling-sunset-season-6/