I would first check to see if you have any public IP address resources that are not associated as these will incur a cost even if not associated.
The easiest way is to just search for 'public ip address' resources using the search feature of the Azure portal.
You can then check if these are already associated to a resource r not. If not, you can associate one of these public IP addresses with the network interface of your VM: https://learn.microsoft.com/en-us/azure/virtual-network/ip-services/associate-public-ip-address-vm#azure-portal
If you need to create a new public IP address first then here is how through the Azure portal: https://learn.microsoft.com/en-us/azure/virtual-network/ip-services/create-public-ip-portal?tabs=option-1-create-public-ip-basic