List of best mirrors for IP address 3.140.185.250, 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-cpp12-dev_12.0.1-19+rpi1+b1_arm64.deb