 when you drop to the tty, run sudo apt update  && sudo apt full-grade.  Reboot, then run plasmashell —replace and everything should be back to normal.
 Correction: normal with the exception kwin_x11 fail to launch....
[11:16] <mparillo> Thank you Darin. I believe the problem was that 5.23.90 is still dropping for me in JJ. I got more components this morning, and I can now login. But the SDDM theme appears missing as well as details from kinfocenter. I will try again tomorrow. 
[11:17] <RikMills> mparillo: yes, it is still not all migrated yet. slow riscv64 builds are holding things up
[11:18] <RikMills> the fix for sddm is in p-w, which is still stuck
[13:07] <BluesKaj> Hi folks
 just ran updates a few minutes ago and everything seems normal on JJ except for Info center is empty... hmmm...
 plamsa-workspace, plasma-desktop plus some other 5.23.90 packages are still in proposed (re @DarinMiller: just ran updates a few minutes ago and everything seems normal on JJ except for Info center is empty... hmmm...)
 very good.
 they should migrate in the next few hrs I hope
 How would I observe the help packages/website?
 /help/held
 https://people.canonical.com/~ubuntu-archive/proposed-migration/update_excuses.html#kde-cli-tools
 oooh, the eye chart :)
 depends what you are viewing it on :P
 the blocking thing there is a missing plasma-desktop build on riscv64
 that HAS actually completed, so once published and that fact gets picked up, things should migrate