Because Bundler versioning is a pain, their Docs point us in the direction of getting the right version installed:
gem install bundler -v "$(grep -A 1 "BUNDLED WITH" Gemfile.lock | tail -n 1)"
Solution originally sourced from here: https://bundler.io/blog/2019/05/14/solutions-for-cant-find-gem-bundler-with-executable-bundle.html
- Lanny Bose on an M1 MacBook Pro on MacOS 12.6.1