I use to be able to ping my son’s iPhone through the Find My IPhone app. Now it seems I can only ping my phone. Did you remove that feature?

That’s what it’s always done. Instead of choosing your son under People choose his phone under Devices. You are looking for the phone, not for your son, who neural system doesn’t run iOS. People can have multiple devices; for example, my wife and I each have an iPhone, an iPad, an Apple Watch, AirPods and a Mac. If I’m looking for one of them I don’t want them all to alert.

BTW, while you masked some of the content in the image, it still contains personally identifiable information. I’ve asked the hosts to delete the image.

It still works on my famly's phones. I go to https://icloud.com/find, choose a phone from the dropdown list and see this:

When I click on Play Sound it still plays a sound.

And when I open the Find My app on my phone, tap on Devices, then a device I still see Play Sound, and it still works.

Both work regardless of the Mute switch setting.

It should still work. On your son’s phone make sure that it still has permission for you to track it.

https://getsupport.apple.com/