Did the Text Mesh Pro namespace change?

The namespace is correct.

for instance to change the text all you would need is the following:

 using TMPro;
 using UnityEngine;
 
 public class ClassName : MonoBehaviour
 {
     private TextMeshProUGUI textMeshProUGUI;
 
     private void Start()
     {
         textMeshProUGUI = GetComponent<TextMeshProUGUI>();
         
         textMeshProUGUI.text = "New text";
     }
 }

Hope this helps.

So I solved my own problem. I went to the TextMesh Pro option window in the editor (Window->TeshMesh Pro), and imported the "TMP Examples and Extras." I had already imported the Essentials, but apparently, there's something missing from essentials that stops Visual Studio from recognizing the namespace. Anyway, I didn't include the example scenes on my import and it still worked. Hope this helps other. I'm sure it will get fixed eventually :).

Another reason this might not work is if the assembly you're working in does not reference the TextMeshPro one. The image below shows what a valid reference might look like:

This solution worked for me: https://forum.unity.com/threads/namespace-tmpro-not-found-in-test-runner-test.541387/#post-3570214 Pasting here: The step that I missed which is causing the issue is related to the use of an Assembly Definition in this created test folder.

The solution is to manually edit the .asmdef to add a reference to the Unity.TextMeshPro assembly.

In order to do so, select the file and use the context menu "Show in Explorer" and then open the file in some text editor to make the following changes..

 {
     "name": "Tests",
     "references": [ "Unity.TextMeshPro" ],
     "optionalUnityReferences": [ "TestAssemblies" ]
 }