UI no longer displays the "Custom message when sign-ups are not available"

[downeymj]

Steps to reproduce the problem

1. Go to https://mastodon.example.com/admin/settings/registrations, e.g.
2. Close registrations to an instance by changing the value of the "Who can sign-up" dropdown to "Nobody can sign up".
3. Enter a custom message in the "Custom message when sign-ups are not available" text box.
4. Click the "Save Changes" button.

Expected behaviour

The custom message should appear to logged-out users when clicking the "Create account" button, at the https://mastodon.example.com/auth/sign_up URL, and when clicking the "Sign up" link at the bottom of https://mastodon.example.com/auth/sign_in.

Actual behaviour

The message does not appear in any of these places. The "sign_up" link redirects back to the main page. The "Sign up" link at the bottom of the "sign_in" page goes directly to joinmastodon.org.

Detailed description

No response

Mastodon instance

floss.social

Mastodon version

v4.2.8

Browser name and version

All

Operating system

N/A

Technical details

No response

[nemobis]

Probably related to #21556?

Do you remember whether it ever worked in v4.1 or later? In the past year the "closed registration modal" only seems to have been touched by across-the-board refactorings:
d27216d
d1b057a