using Google MLKit Barcode scanning memory leak

I used the following code：

private var zoomCallback = ZoomSuggestionOptions.ZoomCallback { zoomLevel: Float ->
camera!!.cameraControl.setZoomRatio(zoomLevel)
true
}
private var barcodeScanner = BarcodeScanning.getClient(
BarcodeScannerOptions.Builder()
.setBarcodeFormats(Barcode.FORMAT_QR_CODE)
.setZoomSuggestionOptions(ZoomSuggestionOptions.Builder(zoomCallback).build())
.build()
)

override fun onDestroy() {
super.onDestroy()
barcodeScanner.close()
}

Always in GC when service is destroyed
I tried removing "camera!!.cameraControl.setZoomRatio(zoomLevel)"
Fixed memory leak
What is the reason?