brew gem install neovim requires gcc@5 formula and crashes if the formula is absent

[JuPlutonic]

Ubuntu 18.04:
/usr/bin/gcc version 10
gcc-7 /home/linuxbrew/.linuxbrew/bin/gcc-7
/usr/bin/gcc-10
gcc-11 /home/linuxbrew/.linuxbrew/bin/gcc-11

brew gem install neovim works only if you have gcc@5 preinstalled.
Now homebrew comes with /home/linuxbrew/.linuxbrew/bin/gcc version 11 not 5, but installation happens with
this command (see it in /home/linuxbrew/.linuxbrew/Cellar/gem-neovim/0.9.0/extensions/x86_64-linux/3.0.0/msgpack-1.4.2/mkmf.log): "gcc-5 ....."