SHA256 fingerprints are bad for the user experience
Over in https://lists.gnupg.org/pipermail/gnupg-devel/2021-August/034958.html Werner observes that using SHA256 for fingerprinting creates a bad user experience. I agree.
Whether we like it or not, comparing fingerprints is often the only way to authenticate OpenPGP certs. People print them on business cards and hand them out, people compare them at key signing parties, people include them in email footers.
Hex(SHA256(..)) is 64 characters, even without pretty printing. That is not only terrible for comparisons, it also creates problems for simply displaying the values.
Imagine printing intended recipients on a 80x25 terminal:
Intended Recipient: 98ea6e4f216f2fb4b69fff9b3a44842c38686ca685f3f55dc48c5d3fb110
7be4
Oops. I imagine GUI applications having similar space limitations and hence layout problems with that kind of fingerprint.