Used the “Set Variable to text” action on a bunch of variables named…
Now, in the variables list in “Preferences” their content is shown as “Password”.
Also, I cannot delete them. Delete button in the Preferences doesn’t do anything. AppleScript also doesn’t do anything.
“Detect (and Conceal) Possible Passwords” is disabled. I also tried restarting Keyboard Maestro engine. Doesn’t change anything.
The problem goes away as soon as I remove the two underscores from the names of the variables (although the old variables that contain the two underscores still persist in my variables list and I cannot get rid of them).
(I used the two underscores because I am employing a user prompt, and everything before the double-underscore is not shown there.)
The actual prefix I used was “pwb__”. And, apparently, the problem wasn’t the two underscores, but the fact that the first two letters are “pw”. Keyboard Maestro seems to interpret this as meaning that the variable contains a password. Which explains why they are treated differently from other variables.
It still seems to be a bug, because according to @peternlewis password variables should not show up in the Preferences at all. I also wonder how I can delete them, now that they are there, because otherwise they remain as dead entries in my variables list.
Otherwise, the solution is simple:
I’ll just use a different prefix for these variables, and will refrain from using the letters “pw” at the start of any of my variables in the future.