I don't think the urgency field is meaningful in Ubuntu, especially for post-release fixes - I believe a package migrates as soon as it's approved and passes builds/tests. The urgency field comes from Debian, which uses it to describe how many days a package should sit in Debian unstable before migrating to Debian testing, in the hopes that if it's buggy, people will file a bug before it migrates to testing. The Debian default is now "medium" (5 days) instead of "low" (10 days), but people with older tools tend to generate changelog entries that say "low". (And even in Debian, I don't think the field has any meaning for post-release updates; I think it only applies to unstable-to-testing migrations.)

Given this seems to be affecting a relatively small number of systems, that's not necessarily unreasonable. It might be very urgent for the people affected, but still low urgency for the userbase overall as compared to other problems.

Though it seems more likely to me that this bug was filed as a placeholder for the already-written patch and verification thereof, and the person filing it simply didn't bother with the urgency field since it wasn't really a bug-report-as-such.

Sorry fam - security issues are more important ¯\_(ツ)_/¯

The last time I used Ubuntu, they hadn't yet realized what vertical display synchronization is, and nobody had explained to them that you don't do your rendering on the framebuffer you're currently scanning out. So an occasional boot of the recovery kernel truly vanishes behind the plain broken display they expect you to put up with.