List of best mirrors for IP address 3.139.69.138, located in an unknown country.
I am very sorry, but no mirror was found. Feel free to download directly:
http://mirrordirector-mb.raspbian.org/multiarch/pool/main/l/llvm-toolchain-12/libclang-common-12-dev-dbgsym_12.0.1-19+rpi1+b1_arm64.deb