KDE Plasma in FreeBSD ports is still version 5.24.6 (in ports HEAD, while the quarterly has 5.24.5). It will remain stuck at that release for a while longer.
KDE ports are mostly administered in the
Mk/Uses/kde.mk file in the
FreeBSD ports tree. You can look in there to see what the current versions
of most-everything is. Individual ports (e.g.
x11/konsole) defer to
settings in that centralized administration. Right now it says
KDE_PLASMA_VERSION?= 5.24.6 KDE_PLASMA_BRANCH?= stable
Why? Passwords. KDE Plasma 5.25 wants to talk to PAM for passwords – locking and unlocking of the screen, for instance. The infrastructure for that was not there by default on FreeBSD. There’s this Phabricator review for FreeBSD that adds part of the puzzle. Here is a PR adding a possibly-relevant PAM module, from a year-and-a-half ago. So the pieces of the puzzle are there, just not assembled yet (or maybe they’re scattered on the floor and we need to go looking).
So all those lovely KDE Plasma releases for the 5.25 series, with look-and-feel and colors improvements, will have to wait a bit longer. Not much use having a beautiful lock screen with configurable look-and-feel and colors, and no way to unlock it.