In Plasma with Wayland I configured the screen to turn off and lock after 5 minutes. To "turn" the screen back on I start typing my login password, but curiously the first key corresponding to my password is not typed, but the others are. I have already checked my PC's keyboard and it is working normally, including the key itself that Plasma did not detect. To confirm my hypothesis that Plasma was not picking up the first key typed, in a similar scenario, I typed a sequence of keys different from my password and discovered that the same thing happened, Plasma did not pick up the first letter typed, but when I tested it in X11/Xorg everything worked normally.
Moving to screen locking component
This worked just fine in 5, but in 6 the first letter is being ignored, so the first login attempt always fails, and then there's a delay, and swearing, and breaking the keyboard, and then you need a new keyboard, and the wife complains about the swearing and noise, and then the resulting divorce (although this happens only once per marriage), so maybe we instead could go back to how it worked in 5 where no letters were ignored.
Is this a duplicate of https://bugs.kde.org/show_bug.cgi?id=488516 ?
It does look like a duplicate, thanks for finding that ticket. Let's close this one. *** This bug has been marked as a duplicate of bug 488516 ***