Yes and there is a actually a blue teacup and teapot set that travels across all these dimensions.
There are multiple castles, tea cups, background silhouettes, gemstones and others in these manhwas because they pull from a collective to fill each page. This particular castle's name is Castle Nim. You can find it on google in different colors from different manhwas. :D
That’s kind of cool and lazy at the same time (▰˘◡˘▰)
Well, drawing is a lot of work. Then the added coloring is a pain. I tried to once and didn't make it past 4 panels before I gave up... so having stock images for details like backgrounds or items really saves a lot and gets us these chapters out faster! But is is cool and fun to imagine all the castles and items were isekai'd LOL
I know, art takes time and a ton of effort. I was just kidding :)
There is a particular Victorian-style glass-covered floral conservatory with reflecting pool that jumps around the different palaces, too. If the production company makes use of hackneyed plots and stereotyped characters, it's no surprise that the background art is also stocked.
I’ve noticed that same castle exterior in other manhwas. The two buildings connected by a bridge. I like to pretend the manhwa characters and stories live in that same place but in different dimensions (▰˘◡˘▰)