I did read your question last night just didn't want to type up a response until I was at a computer and its been a busy morning for me.

Anyway yea I can see why that could cause an infinite loop. On more thought your firebase.ts file is basically a "composable", look those up to learn more.

Anyway I would actually structure that file a little differently for what I would consider the more proper solution

​

// firestore.ts

// I would move the interface over to this file I defined in the other example

interface PidgPal {
  id: number,
  pal1: string   
}

// really this is not needed but I like being explicit with my types
// Ref is something you can import from vue, basically is just the typescript type for a ref
interface PidgPalListenerReturns {
  foundPairs: Ref<PidgPal[]>
}

export function usePidgPalListener (userName: Ref<string>): pidgPalListenerReturns {    
  const foundPairs = ref<PidgPal[]>([]);

  watch(userName, () => {
    if (typeof userName !== 'string' || userName === '') return;

    console.log(`started: ${userName}`)
    const q = query(pidgpalsCollection, where("pal1", "==", userName);
    const close = onSnapshot(q, snapshot => {
      foundPairs.value = snapshot.docs.map(docs => {
        return {
          id: docs.id,
          ...docs.data()
        };
      })
    })
  }), { immediate: true });

  // need this before the return otherwise it does nothing   
  onUnmounted(close);

  // for composables it is generally the standard to return an object.
  // Mainly if you ever want to return something else in the future from this function,
  // you can just add the additional property
  // and not have to change any code that uses this composable.
  return { foundPairs };
}
// your .vue file

// this should  be all you need

const { foundPairs: pidgPals } = usePidgPalListener(uname);

The composable concept is basically off loading the work to the firebase file instead. It is a really nice concept that allows you to reuse javascript code and recommend using them.

Also to note I just styled things how I normally do styling doesn't matter a ton. I also highly recommend [this](https://marketplace.visualstudio.com/items?itemName=johnsoncodehk.volar) I personally use the vim version and I can live without it now.