Bluetooth connection breaks shortly

Arduino UNO with HC-05 or HC-06 Modul
Android Smartphone Google Pixel 3 with Android 10 and latest patches
Blynk Server
Blynk Library 0.6.1

The Code, download from Blynk Homepage:

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial

#include <SoftwareSerial.h>
SoftwareSerial SwSerial(10, 11); // RX, TX
#include <BlynkSimpleSerialBLE.h>
#include <SoftwareSerial.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "rTg70NEFRyps9RIXyBrx97FM_0Y-eaY_";

SoftwareSerial SerialBLE(10, 11); // RX, TX

void setup()
  // Debug console

  Blynk.begin(SerialBLE, auth);

  Serial.println("Waiting for connections...");

void loop()
  // You can inject your own code or combine it with other sketches.
  // Check other examples on how to communicate with Blynk. Remember
  // to avoid delay() function!

When I push the Bluetooth Connection Button in the App at the phone
mostly the Bluetooth connection with HC-05 and 06 does not work from beginning, no connection.
Or when I am connected, the connection is down after a few seconds.

With other apps (Bluetooth Terminal for Android) the connection is very stable