SUMMARY STEPS TO REPRODUCE Unfortunately I haven't able to reproduce it. It happens occasionally. OBSERVED RESULT EXPECTED RESULT SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: Kubuntu 20.04 (available in About System) KDE Plasma Version: 5.18.5 KDE Frameworks Version: 5.68.0 Qt Version: 5.12.8 ADDITIONAL INFORMATION This seems to not be a problem with my computer. I bought it recently and this bug goes away after logging out. The keyboard keys get pressed in the point that I can't even use Control+Alt+Backspace because there is another key being "pressed".
I have experienced this issue as well but I am almost 100% positive it's a hardware issue. This used to happen randomly for me on a 2016 HP Spectre X360, but since replacing it with a 2020 Lenovo ThinkPad X1 Yoga running the exact same software, I have never had the issue recur. So I strongly suspect it was a hardware problem with the old laptop's keyboard. And I similarly suspect that it's the same for you. Since you said that it started happening soon after you bought a new computer, that gives me even more reason to suspect it. :)