SUMMARY Probably two issues, or maybe not. - Copying something from Firefox (& maybe from other apps??) sometimes does not show up in the "Clipboard contents" system tray applet. Then i cannot paste it into other apps (Chrome, Kate, Application Launcher search field) neither with Ctrl + V, nor with context menu. In addition after i try to paste it the app into which i try to paste freezes for a while (4-5 seconds). - If i copy from Authy snap some 2FA code and close the Authy app i'm not able to paste it. It has to be still opened to paste successfully. STEPS TO REPRODUCE 1. Copy something from Firefox 2. Try to paste into Kate/Google Chrome/Application Launcher search field OBSERVED RESULT App freezes for a while EXPECTED RESULT No freeze should happen. Should paste successfully. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.23.4 KDE Frameworks Version: 5.89.0 Qt Version: 5.15.2 Kernel Version: 5.15.7-zen1-1-zen (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz Memory: 7,6 GiB of RAM Graphics Processor: Mesa Intel® UHD Graphics 620
I should say that when i copy from Authy the code appears in the system tray clipboard applet, but still doesn't paste if Authy is closed. Let me know if these should be two bugs.
Similarity to Bug 433854 ? I still encounter the "obstinacy" with Firefox described in https://bugs.kde.org/show_bug.cgi?id=433854#c7 Often see the issue when running client VM's and trying to cut and paste from one to another. See the "5 second freeze" when trying to paste. There is the workround of clearing the clipboard history and trying again. It sometime helps, not a golden bullet.
Apparently the OP in Bug 433854 can't paste into other tabs but i think i can do that, just can't paste into other apps. I'll have to try it the next time a little more. Hasn't happened today and maybe yesterday i believe.
It's more liek https://bugs.kde.org/show_bug.cgi?id=435220
For copying from firefox causing a freeze see: https://bugzilla.mozilla.org/show_bug.cgi?id=1722369 For other plasma issues see the related bugs already cited. Though we need to narrow things down a lot more to be useful