Standardise QR code styling when generated individually vs. in bulk

[halfwhole]

Describe the bug

The QR codes for bulk generated links are stylistically a little different when generated in bulk by the lambda function vs. generated individually by the server

Left: generated in bulk by lambda function, Right: generated individually by server

Apart from the colour difference, there's also a font difference. The right one (created on the backend server) has font IBM Plex Sans (see #1317 for more context), but it doesn't seem to be present on the left one (bulk generated QR code)