Try the below:
$rsvname = "rsv-infra-prod-01"
$infrargname = "rg-infra-prod-sc-01"
$vault = Get-AzRecoveryServicesVault -Name $rsvname -ResourceGroupName $infrargname
Set-AzRecoveryServicesVaultContext -Vault $vault
$backupcontainer = Get-AzRecoveryServicesBackupContainer `
-ContainerType "AzureVM" `
-FriendlyName vmdcprod01
$item = Get-AzRecoveryServicesBackupItem `
-Container $backupcontainer `
-WorkloadType "AzureVM"
Get-AzRecoveryServicesBackupRecoveryPoint -Item $item -RecoveryPointId 7701367240882239739
s
Reference: [https://github.com/petitess/powershell/blob/2e7fdead5d729f4bef347a7eddd8ae74584d99d4/Azure/Get-AzRecoveryServicesBackupRecoveryPoint01.ps1#L13
Note: I don't have any retention points in my test Azure subscription to reference against, but the Get-AzRecoveryServicesBackupRecoveryPoint cmdlet, does point to the correct one to use.
Let me know how it goes.