MediaPlayerService.kt

...
private val prefsListener = SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
      when (key) {
          PrefsRepo.KEY_SKIP_SILENCE, PrefsRepo.KEY_PLAYBACK_SPEED -> {
              invalidatePlaybackParams()
          }
          PrefsRepo.KEY_PAUSE_ON_FOCUS_LOST -> {
              updateAudioAttrs(exoPlayer)
          }
          // \/ \/ Add below \/ \/ 
          PrefsRepo.KEY_JUMP_FORWARD_SECONDS, PrefsRepo.KEY_JUMP_BACKWARD_SECONDS -> {
              serviceScope.launch {
                  withContext(Dispatchers.IO) {
                      sessionToken?.let {
                          val notification = notificationBuilder.buildNotification(it)
                          startForeground(NOW_PLAYING_NOTIFICATION, notification)
                      }
                  }
              }
          }
      }
  }

...

NotificationBuilder.kt

// Just do the same thing you had done to make the notif use current speed icons on each notification build, example below

    private fun skipBackwardsAction() = NotificationCompat.Action(
        getJumpBackwardIcon(),
        context.getString(R.string.skip_backwards),
        makePendingIntent(mediaSkipBackwardCode)
    )


    ...

    builder.addAction(skipBackwardsAction())