I built a free checker for GitHub's Nov 2 change: from that day, pull_request_target workflows stop running on public repositories unless an Actions policy allows them. Paste a repository and you get, in seconds, which workflows are affected and what to do: https://uniteandcreateforlife.github.io/prt-check/

It runs in your browser (nothing is stored) with the same rules as the open-source CLI and GitHub Action. 269 of the 1,000 most-starred repositories use the trigger.