When clicking on plasma-nm applet in the notification area, it opens a relatively small rectangular window around that area. Selecting a connection and Details tab in it shows various details about IP addresses. It works OK for IPv4, but IPv6 addresses are quite longer and they are truncated there without any way to see them fully from that interface. May be use wider window to begin with or detect that IPv6 information is needed and increase it on demand? There is no way to resize that applet interface manually either, which could be another workaround.
I already see enough space in mine to display IPv6 addresses; the only case where there wouldn't be enough space is when the translated text for the labels is really long so it reduces the amount of space for the address--which I can see is possible. In Plasma 5.26, you can resize the pop-up. That should be sufficient to let people self-satisfy here.
Bulk transfer as requested in T17796