This happens on postmarketOS, I don't recall seeing this on the reference Halium builds.
On Qemu (the only platform I got the shell not to crash, different issue unrelated), plasma-nm is displayed wrongly.
On real devices, this seems to even crash the shell completely. The logs show nothing useful.
EDIT: Maybe the crashing is not related to either the plasma-nm or plasma-pa (what I had as a fallback thought) applet, but rather them being based on QML which are known to crash on postmarketOS (we're still figuring out how to resolve that). Focussing the issue on just the applet being shown wrongly for now.