What version of Racket are you using?
Racket v8.4.0.4 [cs] on Windows 10 (using snapshot 20220125-b43e120 from https://www.cs.utah.edu/plt/snapshots/)

What program did you run?
Anything from raco that prompts the user. To reproduce, I chose to install a package with a dependency. First, I uninstall the package and its dependency, and then I reinstall the package:

raco pkg remove helpful levenshtein
raco pkg install helpful

What happened?
A prompt appears, and I press a and hit enter. Nothing happens until I hit enter again, at which point it rejects the input and continues with the default choice:

The following uninstalled packages are listed as dependencies of helpful:
   levenshtein
Would you like to install these dependencies? [Y/n/a/c/?] a

Invalid answer: a
 Answer nothing or `y' or `Y' for "yes", `n' or `N' for "no", or
 `a' or `A' for "yes for all", or `c' or `C' for "cancel".
Would you like to install these dependencies? [Y/n/a/c/?] Resolving "levenshtein" via https://www.cs.utah.edu/plt/snapshots/20220125-b43e120/catalog/
Resolving "levenshtein" via https://pkgs.racket-lang.org
[...]

Note that I do not have an opportunity to pick a choice at the second prompt. It appears to take my <enter> at that point without waiting, going with the default choice.

What should have happened?
It should have accepted my a input.

Please include any other relevant details
This bug occurs on Windows 10, whether I'm using cmd, powershell, or WSL. This bug does not occur with the same version of Racket on Debian.