Yeah because it identifies itself as such. But each version on Manjaro or Arch are gonna report as Manjaro or Arch. With Ubuntu you have two releases every year that each report as a unique name.
It's interesting how fragmented the Linux user base is in the survey. Excluding steam deck from the equation, the visible versions of Ubuntu are getting roughly 18.6%, Arch is getting like 14% of the desktop and Mint 21.3 getting 8.5%. The Flatpak version does put confusion into the data (hiding 11% of desktop versions) and the missing "other" 22.94% group accounts for 39% of the desktops so there may be lots of other version fragments hidden away, but regardless no single distro version seem to dominate.