@Dhimant Patel - Welcome to Microsoft Q&A and thanks for reaching out to us.
The "default" value in the response of the az billing balance show
command indicates that the billing profile has not been set up yet. This usually means that there is no balance available for the billing profile.
If you have set up the billing profile and still see "default" as the balance, it could be because the billing profile has not been fully provisioned yet.
It can usually take up to 24 hours for the billing profile to be fully provisioned and for the balance to be available.
Hope this helps. and please feel free to reach out if you have any further questions.
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