Hey there kristiana241,
We understand that one of the cameras on your iPhone 11 Pro has a dark spot with all pictures. We'll be happy to help with this.
To begin, the best first steps for issues like this can be found in the section "If the camera isn't working" here: If the camera or flash on your iPhone, iPad, or iPod touch isn't working
This will guide you through a few steps that may help like removing the case and cleaning the lens with a microfiber cloth.
If the issue persists after going through those, there might be a hardware issue. Having it inspected would be a great option. To see what options are available for that, reach out to Apple support here: Get Support
We hope this helps!