Hi there,
I recently installed KDE Connect. I am on Linux Mint 20.2 64bit (Uma) with Cinnamon DE. I had no problem (minus vpn) issues installing KDE connect. I installed the Android application on Android 11 without a problem as well. They paired, and everything seems to work fine. Pinging back and forth, mobile control of the computer mouse, sending files, clipboard sync, etc. However I have ONE weird issue, and that is that KDE Connect SMS on the desktop is showing a non-existent ghost text message that my phone does not have. I only have one texting program (default google messages) on my phone, it has no blocked/spam/archived messages. The message in question is from Google, a gmail/google service verification from one of those short 6 digit numbers (your verification code is G-XXXXXX) tier messages. I can load it from KDE Connect SMS, I can see it in the left with the messages, but the loading symbol never goes away. Refreshing/unpair & repair does nothing, also like I said, it's a fresh install (of KDE Connect) on both the computer & phone. Clearing cache/force closing for the android sms program did nothing. Rebooting both devices did nothing. When I do device pair through google messages onto google messages web, said ghost text doesn't show up either. I installed SMS Backup & Restore and did a complete SMS/MMS & call backup of my phone, and that also does not show the ghost message in question. Obviously KDE Connect just grabs what is on my phone, so it must be a stuck message on androids end somehow, but since only KDE Connect SMS is showing it is very odd. Like I said EVERYTHING works, but I figured I would report this error, and really wasn't sure how to explain/word it doing it directly through bugs.kde.org.

edit: Seems the ghost message did not like being reported and has vanished randomly. If you experience this problem, it might just go away after a few reboots/unpair/repairing sessions.