Allocation failed. We do not have sufficient capacity for the requested VM size in this zone

Unfortunately, it looks like this SKU of VM isn't available in this zone, you have a few options:

1. Check to make sure you can request Quota for your Subscription: Increase regional vCPU quotas.
2. Try another Zone, ie 2 or 3 (although I suspect its a Regional issue).
3. Try a separate SKU size
4. Try a v3 SKU. Sometimes the older SKUs can be used.
5. The IP address if set to Static, should remain the same, unless you are recreating the VM from scratch, in which you can unattach it from one VM and attach it to another, or delete the NIC and reuse the same IP on your new VM..

Hi Anh Hua,
Based on your query,
If your subscription has insufficient quota for the requested VM size, you'll need to raise a quota increase request first. as mentioned, Luke Murray document
Instructions on how to achieve this thing mentioned below
Once that's approved, use the Azure CLI command
az vm list-skus --location southeastasia --size Standard_NC24ads_A100_v4 --output table to check which zones support the VM series SKU.
SS

If you want to retain the same public IP address you have to use standard only instead of basic mentioned below SS. when deploying the VM in another zone, start by stopping and deallocating the existing VM. Before detaching the primary NIC, create a secondary NIC, assign it to the VM, and then detach the primary NIC.
SS

Please refer the documentation for more information on standard and basic
When you create the new VM in the same region, attach the same NIC to ensure the public IP is retained. If you're using a Standard SKU public IP, it will automatically be set to static. Follow these steps to successfully keeping the public IP and ensuring the specifications remain unchanged.
Please refer the documentation for detaching and attaching the NIC
If you have any further query, please let me know