Bunderでplatform=rubyを強制する
bundler
BUNDLE_FORCE_RUBY_PLATFORM=1
または
bundle config set --local force_ruby_platform true
または
bundle config set --global force_ruby_platform true
force_ruby_platform (BUNDLE_FORCE_RUBY_PLATFORM): Ignore the current machine's platform and install only ruby platform gems. As a result, gems with native extensions will be compiled from source.
https://bundler.io/v2.6/man/bundle-config.1.html