Missing deploy previews

[redoomed1]

Bug description

The most recent PR I submitted (#2624) did not generate a GitHub Actions preview.

Additionally, existing preview links for open PRs no longer function (i.e., they return "Site Not Found" error pages).

Affected pages

No response

Browser

No response

Operating System

No response

Before submitting

• [X] I am reporting something that is broken on the website, not making a suggestion.
• [X] I agree to the Community Code of Conduct.