ExoPlayer adds an additional empty subtitle track not present in the HLS playlist

Media3 Version

ExoPlayer 2.18.7

Devices that reproduce the issue

• Samsung Galaxy S21 running Android 13
• NVIDIA Shield running Android 11

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Yes

Reproduction steps

1. Add the provided samples to media.exolist.json
2. Play Subtitle samples > Sample 1 (broken)
3. Open text track selector/subtitle dialog

Expected result

Only the subtitles given in the HLS playlist are shown in the track selector/subtitle selector dialog

Actual result

An additional subtitle choice with no label ("Unknown") is shown

This is a screenshot from a breakpoint in onTracksChanged() when playing Sample 1 (broken). There are two groups with type=C.TRACK_TYPE_TEXT, but the HLS playlist only contains one subtitle. The first group (id=main:muxed:2) is the erroneous one

Media

Some samples to be added to media.exolist.json:

{
  "name": "Subtitle samples",
  "samples": [
    {
      "name": "Sample 1 (broken)",
      "uri": "https://nrk-od2.telenorcdn.net/open/ps/mynt/mynt25000121/8092c2d8-4.smil/muxed.m3u8?adap=small"
    },
    {
      "name": "Sample 2 (works)",
      "uri": "https://nrk-od2.telenorcdn.net/open/ps/nnfa/nnfa19060123/a2fff27f-7.smil/muxed.m3u8?adap=small"
    }
  ]
}

Bug Report

• You will email the zip file produced by adb bugreport to dev.exoplayer@gmail.com after filing this issue.