Availability Group Listener and old client software
In your question, you included the following check to validate that you've set the RegisterAllProvidersIP to false:
PS C:\&gt; get-clusterresource &quot;Cluster Name&quot; | Get-ClusterParameter RegisterAllProvidersIP

Object       Name                   Value Type
------       ----                   ----- ----
Cluster Name RegisterAllProvidersIP 0     UInt32

If you've used the Cluster Name then you have set the RegisterAllProvidersIP parameter on the wrong object.
There are several similarly named objects in your screenshot:

The Windows Cluster: WC01
The Availability Group: AG01
The AG Listener: AGListener01

To validate how the setting is configure, you should use the listener name not the cluster or AG name:
PS C:\&gt; Get-ClusterResource AGListener01 | Get-ClusterParameter RegisterAllProvidersIP

Or, to do this a bit more stepwise, you can do Get-ClusterResource and you'll see something like this:
Name                         State   OwnerGroup     ResourceType
----                         -----   ----------     ------------
10.10.10.199                 Online  Cluster Group  IP Address
Cluster IP Address           Online  Cluster Group  IP Address
Cluster Name                 Online  Cluster Group  Network Name
AG01                         Online  AG01           SQL Server Availability Group
AG01_10.10.20.138            Offline AG01           IP Address
AGListener01                 Online  AG01           Network Name
File Share Witness           Online  Cluster Group  File Share Witness
IP Address 10.10.10.138      Online  AG01           IP Address

Out of all of these things, we only care about the objects that belong to the OwnerGroup for the AG. We can filter a bit further with Get-ClusterResource | Where OwnerGroup -eq AG01:
Name                        State   OwnerGroup   ResourceType
----                        -----   ----------   ------------
AG01                        Online  AG01         SQL Server Availability Group
AG01_10.10.20.138           Offline AG01         IP Address
AGListener01                Online  AG01         Network Name
IP Address 10.10.10.138     Online  AG01         IP Address

These 4 items represent the resources that make up my AG: The AG itself, the listener (listed as &quot;Network Name&quot;), and the two IP addresses, each in different subnets.
The item that I want to check for the RegisterAllProvidersIP parameter is the listener  (Network name) resource: Get-ClusterResource AGListener01 | Get-ClusterParameter will give me the full list of parameters on the Listener object:
Object        Name                   Value                            Type
------        ----                   -----                            ----
AGListener01  Name                   AGListener01                     String
AGListener01  DnsName                AGListener01                     String
AGListener01  Aliases                                                 String
AGListener01  RemapPipeNames         1                                UInt32
AGListener01  HostRecordTTL          1200                             UInt32
AGListener01  RegisterAllProvidersIP 1                                UInt32
AGListener01  PublishPTRRecords      0                                UInt32
AGListener01  ResourceData           {1, 0, 0, 0...}                  ByteArray
AGListener01  StatusNetBIOS          0                                UInt32
AGListener01  StatusDNS              0                                UInt32
AGListener01  StatusKerberos         0                                UInt32
AGListener01  CreatingDC             \\dc01.am2.co                    String
AGListener01  LastDNSUpdateTime      9/29/2020 3:57:12 PM             DateTime
AGListener01  ObjectGUID             abc1234def567890ab12cd3456ef7890 String
AGListener01  DnsSuffix              am2.co                           String
AGListener01  ADAware                1                                UInt32

And I can get the specific parameter by explicitly asking for it Get-ClusterResource AGListener01 | Get-ClusterParameter RegisterAllProvidersIP
Object        Name                   Value  Type
------        ----                   -----  ----
AGListener01  RegisterAllProvidersIP 1      UInt32

If this is not set to 0, then you would need to use the block of code outlined in the docs, and be sure you're using the Listener name, and not the Cluster name. The example also recommends setting the TTL as well (picking an exact number is up to you, though the docs suggest 300 seconds). Note that offlining &amp; onlining the Listener is necessary for the new settings to be picked up by the DNS name:
Get-ClusterResource AGListener01 | Set-ClusterParameter RegisterAllProvidersIP 0   
Get-ClusterResource AGListener01 | Set-ClusterParameter HostRecordTTL 300  
Stop-ClusterResource AGListener01 
Start-ClusterResource AGListener01 

After this is done (and the old TTL is expired), you'll be able to see the Lister has only a single IP address configured:
Resolve-DnsName AGListener01