How to reproduce the issue?
My case, I try deleted / copy and paste few text files in Dolphin but no notifications at all.
Try extract a file, it should trigger a notification.
No notification after extracted file.
Track change notification from Audacious works fine (appear and disappear).
notify-send works as well (appear and disappear).
The only ones that seem to stay for me are when I extract a file, all the others work as expected.
Okay, I can reproduce the issue by trying to compress the folder. The notification appears, but it doesn’t disappear.
The same thing happens to me too.
Same happens to me. I also have this bug with notifications from Firefox. When a download is finished, the notification doesn’t disappear. I have to close them manually.
A fix for the notification issue was released, plasma-workspace 6.6.5-2.
Fingers crossed that this will work. 
Yes, it does work. upgraded plasma-workspace (6.6.5-1.1 -> 6.6.5-2.1) (@Cachy & Fedora)
Yer confirm update now and this is fixed/
All is good so far after the update here as well.
Yep, updated, restarted Plasma Shell, problem solved = Happy User!! 
I just noticed that the post-extraction file/folder notification isn’t appearing for me. Is anyone else experiencing this same issue?
Now that you mention it, I’m experiencing the same issue. I hadn’t noticed because I usually extract files from the terminal.
Thanks, at least I know I’m not alone. That issue is not a big deal. I’m just curious 