Error deploying backend to Azure App Service due to slot conflicts (ghost deployment slots)

Question

I’ve been experiencing an issue deploying my Node.js + Express backend to Azure App Service using GitHub Actions. Previously, I utilized deployment slots to manage staging and production deployments. After deleting some of these slots, Azure still seems to reference them internally, causing persistent deployment errors.

When deploying via GitHub Actions (automatic deployment), the deployment appears successful, but the service returns a 404 (Not Found) error. It seems Azure is internally routing the deployment to a slot or reference that no longer exists (what I’d describe as a "ghost deployment slot").

I’ve already tried the following without success:

Completely deleting the affected App Service and recreating it from scratch.

Reconnecting the GitHub repository to Azure App Service.

Ensuring my package.json, server.js, and deployment configurations are correct (previously verified working).

Confirming the backend runs correctly locally and worked fine before slot deletion.

Has anyone encountered a similar issue with ghost deployment slots or persistent internal references in Azure? What steps can I take to fully clear Azure's internal references to old deployment slots and successfully deploy a fresh backend without encountering this issue again?