For those that are still struggling with the camera, I installed Open Camera v1.51.1 and actiated the Camera2 API, which enables switching to manual focus among other features. With manual focus, I can take relative focused images at close range, but whatever focus I set, the images are much more fuzzy than images of the same objects taken with my son's phone, which is the same phone but still with the stock ROM. This is the case for both close and long range images. Turning on DRO makes the images somehow nicer, but still a long way from the quality with the stock ROM. Just fuzzy, with little details and dull colours.