Since the migration to stack heroku-20, wkhtmltopdf doesn't work anymore.
The PDF generation raise this error :
Command Error: /app/vendor/bundle/ruby/2.7.0/gems/wkhtmltopdf-binary-0.12.6/bin/wkhtmltopdf:48:in `<main>': Invalid platform, must be running on Ubuntu 16.04/18.04/20.04 CentOS 6/7/8, Debian 9/10, or intel-based Cocoa macOS (missing binary: /app/vendor/bundle/ruby/2.7.0/gems/wkhtmltopdf-binary-0.12.6/bin/wkhtmltopdf_ubuntu_20.04_amd64). (RuntimeError)
I have the same issue with the version wkhtmltopdf-binary-0.12.5 and wkhtmltopdf-binary-0.12.6