Hi,
We are not able to use environment variable - GITHUB_BASE_REF and GITHUB_HEAD_REF in creating the slot command.
az webapp deployment slot create
We are using -slot along with GITHUB_BASE_REF or GITHUB_HEAD_REF. This is not passing blank value in slot name.
Can you check the issue?
Here is gist - https://gist.github.com/gbohra/c10ce7701e4fcdb2ac708a10727a870d