Now if a key from someone else is expired KMail does not try to get a new one via WKD so users have to do that manually. To increase the usability KMail could automatically fetch a new key via WKD if a key is expired. It could so when the user enabled WKD in the settings.
If you look in Kleopatra under the column "source". Does it say WKD? In that case GnuPG should do this, sadly it does not do it automatically but only if we retrigger a --locate-key so KMail might have to do that.
I have referred this in our task to update the key selection dialog in KMail so that we keep it in mind there. In that keyresolver this might already have been fixed. https://dev.gnupg.org/T6198