Default packages seem not to be upgraded to version 17 on arm64

I’m working on two Ubuntu 22.04 machines, one of whose architecture is x86_64, and the other’s is arm64.
I did the same things on these two machines:

  • Add to /etc/apt/sources.list.d/llvm.sources.list:
    deb llvm-toolchain-jammy main
    deb-src llvm-toolchain-jammy main
    # 15
    deb llvm-toolchain-jammy-15 main
    deb-src llvm-toolchain-jammy-15 main
    # 16
    deb llvm-toolchain-jammy-16 main
    deb-src llvm-toolchain-jammy-16 main
  • Retrieve the archive signature:
    sudo wget -O /etc/apt/trusted.gpg.d/
  • Run sudo apt update.

Then I ran apt policy llvm to check the version of the default llvm package. On the x86_64 machine, it shows that the version is 17. However, on the arm64 one, the version is still 14, and the package belongs to Ubuntu’s default software source. Moreover, no candidate from llvm software source is found. And I have to run sudo apt install llvm-17 to get the latest package.
Does the default llvm package lack an arm64 version? Or is there anything wrong with my configuration and installation?

I visited this page and found that there are only default llvm packages of amd64 version. Why does the default llvm package lack an arm64 version?