Configure Container App behind Front Door with Custom Domain

fstipanovic-stemi Could you please elaborate "ACA has failed to auto renew" - are you using a free certificate to secure the ACA custom domain binding? If thats the case, the CNAME should point to the container app's IP address (or) FQDN and not the FD. Otherwise, the certificate issuance and/or renewals will fail (Ref: Custom domain names and free managed certificates in Azure Container Apps | Microsoft Learn)
For your setup (ie. CNAME pointing to FD), you should use your own (existing) certificate - Custom domain names and certificates in Azure Container Apps | Microsoft Learn