Contrast, not colour
A scanner does not see your brand palette, it sees light and dark. This page measures the relative luminance of the two colours you pick and warns you when they fall below a 4:1 ratio, because under a venue light or a phone camera's auto-exposure a pair that looked fine on your monitor turns into mush. Deep colours on white are safe. Two mid-tones are not, and no amount of wanting it to work will change that.
Error correction is a budget, and you spend it
Every code here is built at error correction level M, which means about 15% of the modules can be unreadable and the link still resolves. That margin exists for the real world: a thumbprint, a crease, a bad print run, glare from a window. A centre logo spends most of it before anything has gone wrong. Shorter links help too — a short URL needs a lower version, which means fewer and bigger modules, which means an easier read from further away.
PNG for screens, SVG for print
The PNG is a fixed grid of pixels at the size you chose — right for a story, a thumbnail or a slide. The SVG describes the same code as shapes, so a printer can scale it to a metre without a single soft edge. If you are sending artwork to anyone who will lay it out for you, send the SVG and tell them not to rasterise it and not to place anything over the quiet zone.