How it worked for me to add a matter accessory with my iphone IOS 16.5.1 (Eve energy plug)

1. Open Home
2. Click on the + on the right top to add an accessory
3. Do not find the QR-code with the camera BUT click on the link "More options...."
4. Wait until the accessory is shown (in my case I first had to reset my Eve energy plugs by pressing the button on the plug for ten seconds until the led light flashed red five time; as described in the little manual how to reset the plug)
5. When the accessory is found the select it and THEN use the camera to find the QR-code for pairing purposes
6. Then it said it could take up to minute and it worked

NB: So, for me somehow it didn't work to directly find the QR-code to pair with the accessory. I tried all sorts of things and finally the above steps worked for me.