In this version (YouTube) of "Sing", Bob and Luis are in the arbor which has a fence with what looks like palm tree leaves painted on it.
Does anyone know how long that set lasted? We know this version of the song has an EKA of Episode 0543 (season 5) and that Luis first appeared in season 3; I'm trying to figure out if there's potentially an earlier appearance.
A quick look through some clips of the end credits on YouTube shows that the painted palm tree on the fence was present from seasons 2 (YouTube) through 8 (YouTube), and was removed by season 9. (YouTube)
I went through several of the full season 8 guides. It's present in Episode 0974. By Episode 0997 it's gone (or at least very heavily faded). So it appears that during a production break -- while re-aired episodes were being used -- the mural was removed.
Speaking of going through the guides and looking at the arbor, is it sad that I've gone through the Season 19 guide, just to see the subtle transformations that took place in the area over the course of that particular season (i.e. how the painted brick surfaces were gradually replaced with textured brick surfaces, among other subtleties)?
I can also kind of see why they completely replaced the painted flat behind the fence as well: you look at some of those later Season 18 episodes, you can sort of tell the older flat was warping and wrinkling.