а ты пробовал require 'faker' в консоли приложения?
LoadError: cannot load such file -- faker from /home/dv/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
LoadError: cannot load such file -- faker from /home/dv/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
в rails c LoadError: cannot load such file -- faker from /home/dv/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/bootsnap-1.5.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'