Amp-Stories background audio cuts off after slide 2 on mobile devices

### Description

We have a tap story featuring short videos, set to a single background audio track. Usually if one triggers the audio and taps through the story, the background audio will continue to play through the entire piece — until today. I checked our latest amp-story and found it always cuts after the second slide — across all our pieces actually, which did not used to have this issue. I have not begun to dig through the recent pull requests to try and identify the introduction of this issue, but I intend to do so in the next few days. Has anyone else experienced this issue?

Note: This not a problem within amp pages on desktop. It only affects mobile as far as I have seen.

### Reproduction Steps

Example link: https://www.frame.media/undercovered/silent-deregulator

Turn on the sound and tap ahead two slides. The sound will most likely cut. I would love to hear that it does not.

### Relevant Logs

```shell
No console errors on mobile, as far as I have been able to pick up.
```

### Browser(s) Affected

_No response_

### OS(s) Affected

iOS 15.1.1

### Device(s) Affected

iPhone 13

### AMP Version Affected

2112032204000