A recursive QR code.
@PhilA Yup! I wrote a bit about it at https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capital-letters-smaller-than-qr-codes-with-lower-case-letters/
Which app did it try to load?

Take a look at these two QR codes. Scan them if you like, I promise there's nothing dodgy in them. Left is upper-case HTTPS://EDENT.TEL/ and right is lower-case https://edent.tel/ You can clearly see that the one on the left is a "smaller" QR as it has fewer bits of data in it. Both go to the same URl, the only difference is the casing. What's going on? Your first thought might be th…