Build log

-----> Building on the Heroku-20 stack
-----> Determining which buildpack to use for this app
 !     Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
			Detected buildpacks: Ruby,Node.js
			See https://devcenter.heroku.com/articles/buildpacks#buildpack-detect-order
-----> Ruby app detected
-----> Installing bundler 1.17.3
-----> Removing BUNDLED WITH version in the Gemfile.lock
-----> Compiling Ruby/Rails
-----> Using Ruby version: ruby-3.0.3
-----> Installing dependencies using bundler 1.17.3
       Running: BUNDLE_WITHOUT='development:test' BUNDLE_PATH=vendor/bundle BUNDLE_BIN=vendor/bundle/bin BUNDLE_DEPLOYMENT=1 BUNDLE_GLOBAL_PATH_APPENDS_RUBY_SCOPE=1 bundle install -j4
(文字数制限により省略)
       Bundle complete! 18 Gemfile dependencies, 58 gems now installed.
       Gems in the groups 'development' and 'test' were not installed.
       Bundled gems are installed into `./vendor/bundle`
       Post-install message from sass:
       
       Ruby Sass has reached end-of-life and should no longer be used.
       
       * If you use Sass as a command-line tool, we recommend using Dart Sass, the new
         primary implementation: https://sass-lang.com/install
       
       * If you use Sass as a plug-in for a Ruby web framework, we recommend using the
         sassc gem: https://github.com/sass/sassc-ruby#readme
       
       * For more details, please refer to the Sass blog:
         https://sass-lang.com/blog/posts/7828841
       
       Bundle completed (23.91s)
       Cleaning up the bundler cache.
-----> Installing node-v16.13.1-linux-x64
-----> Installing yarn-v1.22.17
-----> Detecting rake tasks
 !
 !     Could not detect rake tasks
 !     ensure you can run `$ bundle exec rake -P` against your app
 !     and using the production group of your Gemfile.
 !     rake aborted!
 !     TypeError: wrong argument type false (expected Symbol)
 !     /tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:12:in `to_binary'
 !     /tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:12:in `input_to_storage'
 !     /tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:37:in `fetch'
 !     /tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:37:in `load_iseq'
 !     /tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
(省略)
 !     /tmp/build_a51a0b6f/bin/rake:5:in `<main>'
 !     
 !     Caused by:
 !     Bootsnap::LoadPathCache::FallbackScan:
 !
/tmp/codon/tmp/buildpacks/50d5eddf222a9b7326028041d4e6509f915ccf2c/lib/language_pack/helpers/rake_runner.rb:100:in `load_rake_tasks!': Could not detect rake tasks (LanguagePack::Helpers::RakeRunner::CannotLoadRakefileError)
ensure you can run `$ bundle exec rake -P` against your app
and using the production group of your Gemfile.
rake aborted!
TypeError: wrong argument type false (expected Symbol)
/tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:12:in `to_binary'
/tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:12:in `input_to_storage'
/tmp/build_a51a0b6f/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.4.5/lib/bootsnap/compile_cache/iseq.rb:37:in `fetch'
(省略)
Caused by:
Bootsnap::LoadPathCache::FallbackScan: 
(文字数制限により省略)
 !     Push rejected, failed to compile Ruby app.
 !     Push failed

log
1 !     Could not detect rake tasks
2 !     ensure you can run `$ bundle exec rake -P` against your app
3 !     and using the production group of your Gemfile.
4 !     rake aborted!
5 !     TypeError: wrong argument type false (expected Symbol)

このあたりが怪しそうなのはなんとなく分かるのですが、これの原因と対処法が調べても分かりませんでした。

Rubyが3.0.3を実行してしまっていることが原因なのでしょうか？
.ruby-versionで2.6.8を指定しているのですが・・・