User Preferences - Slack Integrations gives a 404

Question

There are several earlier posts tagged status-completed reflecting on this problem, like:

• "Slack integrations" and "Microsoft Teams integrations" in Settings lead to 404
• Integrations with Slack and Microsoft Teams box appear on all sites

but the problem seems to have re-emerged, maybe due to the Staging Ground Teams:

how to reproduce:

1. the link to your Preferences page is accessible via your user-profile: https://meta.stackexchange.com/users/preferences/$your_user_id
2. In the Preferences page you find on your left several Submenus. The one in question is not called TEAMS anymore, but has changed to INTEGRATION. Click "Slack integrations"
3. clicking that link leads you to https://meta.stackexchange.com/users/integrations/slack/$your_user_id which throws a 404