The quiet zone is part of the symbol
Four light modules on every side, unless you deliberately shrink it.
A QR symbol needs a margin of light modules so a camera can see where the pattern ends. This checker’s assumption is 4 modules on every side. The control starts at 4. Drop it and the risk list marks the code. The test sheet forces at least 4 when it draws the print sizes, so a proof you take to the printer is not accidentally margin-free.
The quiet zone is not a design gap you can fill with a pattern. A headline, a rule, or a dark photo in that margin is the same failure as deleting modules.
Drag the code on poster preview until the clearance numbers leave room for that margin inside the trim, not only inside the file.