Welcome to the forum!
Your system is out-of-date. Manjaro's release number currently stands at 20.0.3, and the current 5.6-generation kernel is 5.6.16-1-MANJARO. Please upgrade your system.
Log out of KDE Plasma completely ─ you should see the login screen again ─ and then press Ctrl+Alt+F2. Log in at the character-mode login prompt with your own credentials, and then issue the command...
sudo pacman -Syyu
Answer positively to any questions you might get regarding the replacement of certain packages.
After the upgrade has finished, reboot your system cleanly with...
sudo systemctl reboot
Manjaro is a rolling-release distribution. Updates to the [Stable] branch are generally grouped together in batches and issued on average every two or three weeks. There will always be a dedicated announcement thread about this under the #announcements:stable-updates category.
If you want to keep using your Manjaro system reliably, then it is recommended that you'd pay attention to the update notifier icon in your system tray and/or that you periodically visit the forum in order to check on update announcements.