Why is my Coroutine Continuing to allocate GC from the "MoveNext()" After it completes?

I try to be straightforward in my titles... it's exactly what it sounds like.

I simply call a single Coroutine, which does not call any other coroutines, at any time... I call this single coroutine via the "StartCoroutine(Coroutine())" method at the Start() method.. (this also occurs when I call it from Awake or anywhere really.)

Shouldn't it only be getting called once???

Nevertheless, I am getting MAJOR Lag Spikes from GC Alloc according to the profiler, from this coroutine being repeatedly called... this issue persists in numerous scripts I've written. I'm completely confused rn; I'm about ready to never use Coroutines again...

https://pasteboard.co/HmBHlzE.png (The Image Previewer is not working... lol)

Also, I am NOT calling it from ANYWHERE else, even though it says it's getting called from the Update method, I have triple and quadruple checked with our 'ol friend Ctrl+F... it's ONLY in Start().

Any input is appreciated.

UPDATE:

So I've FINALLY found out what is causing it to continue calling the Coroutine.. though it doesn't make sense.. here's my test:

Code (CSharp):

         private IEnumerator Test()
         {
             while (brainStarted != BrainStarted.True)
             {
                 debugLog = "WAITNG....";
                 yield return null;
             }
  
             debugLog += " - EXITED";
         }

and of course it DOES meet the exit condition after a short time... and surely enough, I DO get the " - EXITED" logged. (debuglog is just a reference to a static UI text Component) although the conditions are met, it continues to call the Coroutine.... I'm continuing investigation - still input is welcome from anyone. The issue is pertaining to while loops inside of Coroutines... this is very strange.

UPDATE:

So only a minor update, but I also noticed this:

https://pasteboard.co/HmBViNr.png

And again, this coroutine (Test()) is merely called one time in the Monobehaviour.Start() method. Via StartCoroutine(Test());

I changed the exit condition from my enum to a bool to verify the issue is not related to the enum... the issue persists.

UPDATE:

Here's an isolated Class I've built for proper testing (still occurring):

Code (CSharp):

 using BrainConnect;
 using System.Collections;
 using UnityEngine;
  
 public class Test : MonoBehaviour {
  
     private bool brainReady = false;
  
     void Start ()
     {
         ConnectBrain.BrainReady += BrainReadyEvent;
         StartCoroutine(TestEnumerator());
     }
  
     private void BrainReadyEvent(object s, System.EventArgs e)
     {
         brainReady = true;
     }
  
     private IEnumerator TestEnumerator()
     {
         while (!brainReady)
         {
             ConnectBrain.debugLog = "WATING....";
             yield return null;
         }
  
         ConnectBrain.debugLog += " - EXITED";
     }
 }
  

This new isolated script is simply attached to a new Empty GameObject Parented under nothing. I get the same results.

https://pasteboard.co/HmC1eu3.png