The gcc-4.8 and g++-4.8 packages have been discontinued in the Ubuntu 20.04 and later default repositories, but they are still available in the Ubuntu 18.04 default repositories. To install the gcc-4.8 and g++-4.8 packages from Ubuntu 18.04 in Ubuntu 22.04 run the following commands:
cd Desktop/
mkdir install_g++-4.8
cd install_g++-4.8/
sudo apt update
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/g++-4.8_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/libstdc++-4.8-dev_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/gcc-4.8-base_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/gcc-4.8_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/libgcc-4.8-dev_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/cpp-4.8_4.8.5-4ubuntu8_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/universe/g/gcc-4.8/libasan0_4.8.5-4ubuntu8_amd64.deb
sudo apt install ./gcc-4.8_4.8.5-4ubuntu8_amd64.deb ./gcc-4.8-base_4.8.5-4ubuntu8_amd64.deb ./libstdc++-4.8-dev_4.8.5-4ubuntu8_amd64.deb ./cpp-4.8_4.8.5-4ubuntu8_amd64.deb ./libgcc-4.8-dev_4.8.5-4ubuntu8_amd64.deb ./libasan0_4.8.5-4ubuntu8_amd64.deb ./g++-4.8_4.8.5-4ubuntu8_amd64.deb
Alternatively to save time you could download all 7 .deb files in a single one-line wget command, but the 7 separate wget commands make it easier to check if you have downloaded all 7 of the required .deb files successfully.