In Ghosts season 3, the revelation that Flower wasn’t gone for good was secretly given away by a subtle hint in her memorial service. The many ghosts from CBSs Ghosts dont stick around on Earth forever. As Sam learned soon after she began communicating with the dead, they can be unexpectedly pulled into the afterlife for good after completing their purpose on earth. This process, which the comically clueless ghost refers to as being Sucked off, happened to a mystery ghost in the season 2 finale of Ghosts. Viewers were left to wonder who was now gone.

https://screenrant.com/ghosts-season-3-flower-return-twist-memorial-clue/