https://petitions.classicpress.net/ is back. This view of past petitions is a bit easier to read and shows more information. Each page links to the corresponding forum thread or category link for further discussion.
As a next step it would be good to add a link from each of the past petitions back to the archive view. There is a full mapping here: subdomain-petitions/urls.json at ea7239c647f5e2b04f9fbd9f452f0fbef6bd1f6b · ClassicPress/subdomain-petitions · GitHub [Edit: this is done now.]