A flat universe? https://futurism.com/the-byte/universe-actually-flat. Chances are they are looking at the 2d (Data) part of a Universe 3dApp (the other parts being 3d Display - Space and 4d Datastore - Spacetime).Flat as in 2d flat. Computer programs are 2d in nature. What appears on your computer screen is usually a table of pixels in the program (raster graphics). The pixels may be generated via 2d polygons (vector graphics). A 3dApp is part of the 3dAbstractions framework that can be used to simulate reality. It is a Windows 10 App written in the VB.Net programming language. It is a type of the 3dSystem that has been described in this post as being a basic Universal pattern. A 3dApp has a basic structure as follows:
App as 3dApp.System
Display as 3dDisplay.System
Data as 3dData.System
Datastore as 3dDatastore.System
Display, Data, Datastore - hence 3d.
Display contains human interface data.
Data contains a database in HFSM format.
Datastore contains persistent data that is usually stored on disk.
All of these systems contain data in 2d/flat format. What you see displayed is usually a 2d image which is turned into 3d by your brain. The database is in 2d format. Persistent data is 4d (think spacetime) in nature but exists in the App as a 2d/flat table.
There is no reason why our Universe cannot exist as a 2d/flat structure, possibly a hologram. See https://www.wired.co.uk/article/our-universe-is-a-hologram. Given Occam's razor, the likelihood that the Universe is a hologram is high. I have discussed this before in this topic.