What is "_vvvvvvvvvvvvvvvvvvvvvvvvvvv2" event?

I am using Firebase Analytics. For my app, it has logged a crash as shown below.

But I can't figure out what the event/log line with the "_vvvvvvvvvvvvvvvvvvvvvvvvvvv2" means. Does anyone have an idea?

Exception java.io.IOException: setDataSourceFD failed.: status=0x80000000
android.media.MediaPlayer.setDataSource (MediaPlayer.java)
android.media.MediaPlayer.setDataSource (MediaPlayer.java:1269)
android.media.MediaPlayer.setDataSource (MediaPlayer.java:1231)...

What is "_vvvvvvvvvvvvvvvvvvvvvvvvvvv2" event?

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