bug: ion-back-button picks wrong route

# Bug Report

**Ionic version:**
[x] **4.x**
[x] **5.x**

**Current behavior:**
I have multiple routes that load the same component with different route props. When clicking the `ion-back-button`, it goes to a different route for the same component, dropping its route props.

**Expected behavior:**
When clicking the `ion-back-button`, it should have the same behavior as using the browser's back button and go back to the url of the previous history entry.

**Steps to reproduce/Related code:**
I created a minimal reproduction of this issue on https://github.com/simonhaenisch/ionic-nav-bug, which has been deployed to [ionic-nav-bug.vercel.app](https://ionic-nav-bug.vercel.app).

The router looks like this:

```tsx

```

To reproduce, do the following:

1. Go to Ionic's profile page (`/profile/ionic`).
2. Go to About page (`/about`).
3. Click the `ion-back-button` (not the browser's back button).

_Expected:_ Goes back to `/profile/ionic` route and shows Ionic's profile.
_Actual:_ It shows Ionic's profile, but the route changes to `/profile` (drops the "name" route prop).

**Other information:**
In this case, using the browser's back button instead works as expected, because unlike `nav.pop` it uses the browser's history stack to go back to the previous url. So I guess a work-around for me would be to implement my own back button that simply calls `window.history.back()`.

Sounds like it could (maybe) be related: #18569.

Start with the ion-back-button and ion-router behavior in the linked minimal reproduction, following the navigation from /profile/ionic to /about and back. Compare nav.pop with window.history.back(); done means the back button returns to the previous history URL, /profile/ionic, without dropping the name route prop.

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