What kind of QR code puzzle could be in a quest game?

A QR code can be a full-fledged puzzle, not just an information carrier. For example, quest organizers can encrypt a number sequence in the code itself that needs to be solved before scanning, or hide a hint in the size and placement of the code in the image - I've come across quests where you had to count the number of modules in the code or collect several codes in a specific order. You can also use visual tricks: change the colors of the code, add a drawing on top of it, or place the codes so that the answer is in their arrangement relative to each other. In my 27 years of work, I don't develop quests, of course, but I really like the logic of these kinds of puzzles - it reminds me of analyzing crop patterns in fields, just in an entertainment format.