You can’t search for pipes/pipe at all in the decal library. It gives the error “Your search request has been redacted for privacy reasons. Please try a different search query.”
Expected behavior
If it worked, I would hope to be seeing decals of pipes and possibly decals of pipes with transparent backgrounds I can use for my train station build.
The more common usage is a literal pipe. Out of context, it should be interpreted as being a literal pipe. This is definitely a bug. In my opinion, at least.
“Pipe” is most likely blocked on purpose. It’s a word that can be associated with things that aren’t really appropriate for younger audiences — like certain drug-related items or slang used in more adult conversations. Even though it has completely normal meanings too, the filter on Roblox tends to block anything that might be misunderstood or misused.