在Android 10中，双摄像头自拍回归的问题可能是由于相机应用默认使用了主摄像头而非前置摄像头造成的。为了解决这个问题，可以在代码中指定使用前置摄像头进行自拍。以下是一个示例代码，演示如何在Android 10上使用前置摄像头进行自拍：

import android.Manifest;
import android.content.pm.PackageManager;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.params.OutputConfiguration;
import android.hardware.camera2.params.SessionConfiguration;
import android.os.Bundle;
import android.view.Surface;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import java.util.Arrays;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST_CAMERA_PERMISSION = 200;
    private String cameraId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 请求相机权限
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
            return;
        }

        // 获取前置摄像头ID
        CameraManager cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);
        try {
            for (String id : cameraManager.getCameraIdList()) {
                CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(id);
                if (characteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_FRONT) {
                    cameraId = id;
                    break;
                }
            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }

        // 打开相机
        try {
            cameraManager.openCamera(cameraId, new CameraDevice.StateCallback() {
                @Override
                public void onOpened(@NonNull CameraDevice cameraDevice) {
                    // 创建捕获会话
                    try {
                        Surface surface = new Surface(/* 需要自定义的SurfaceView或TextureView */);
                        cameraDevice.createCaptureSession(new SessionConfiguration(
                                SessionConfiguration.SESSION_REGULAR,
                                Arrays.asList(new OutputConfiguration(surface)),
                                getMainExecutor(),
                                new CameraCaptureSession.StateCallback() {
                                    @Override
                                    public void onConfigured(@NonNull CameraCaptureSession session) {
                                        try {
                                            // 创建捕获请求
                                            CaptureRequest.Builder requestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                                            requestBuilder.addTarget(surface);
                                            CaptureRequest captureRequest = requestBuilder.build();

                                            // 开始捕获
                                            session.setRepeatingRequest(captureRequest, null, null);
                                        } catch (CameraAccessException e) {
                                            e.printStackTrace();
                                        }
                                    }

                                    @Override
                                    public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                                        // 配置失败处理
                                    }
                                }
                        ), null);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void onDisconnected(@NonNull CameraDevice cameraDevice) {
                    // 连接断开处理
                }

                @Override
                public void onError(@NonNull CameraDevice cameraDevice, int error) {
                    // 错误处理
                }
            }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == REQUEST_CAMERA_PERMISSION) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                recreate();
            } else {
                // 权限请求被拒绝
            }
        }
    }
}

请注意，上述代码只是一个示例，需要结合自己的应用进行适当的修改和调整。