I've recently started using Debian 12 with KDE on my laptop and after ironing out most of the teething issues I have a couple left.
The one I have made no progress on is random freezes on the taskbar. I only really notice this when the clock is wrong (as it's frozen) or I go to click an app on the taskbar and nothing happens. If I press the Meta / Windows key the Start menu appears but nothing else seems to work.
There doesn't seem to be a pattern to it. For example it doesn't always happen resuming from sleep. I can be working away and find it's frozen. I have three widgets running (CPU, Memory and Network) but it froze before I added them. Other than that there is nothing fancy on there.
The workaround is to edit the Taskbar and then drag the resize sliders and it strings back to life with the correct time.
I've done the usual Google Search but haven't found anything that's not been fixed, or recent.
Any help appreciated.
Are you using Wayland with KDE? For me the taskbar freezes if I'm on Wayland and hover over some windows so it shows the preview.
If you're also using Wayland, try turning off window previews (right-click taskbar->configure->Show small window previews).
Also, as a workaround if this doesn't fix it for you, you can execute plasmashell --replace and it'll replace the existing frozen instances instead of starting new ones. If you use krunner (alt+space) it'll stay in your recent commands as well, so you can easily run it again when it freezes again.
I bound that command to meta+del because it was happening frequently enough to annoy the shit out of me. Bring on plasma6!