I have this problem, but when using SSH remote development on an actually remote machine (no WSL) and I need to be able to use the GUI commit button.
From what I have read, the culprit to the GPG not prompting for passphrase is the fact that VS Code uses git -c user.useConfigOnly=true commit --quiet --allow-empty-message --file - -S to commit stuff.
If the --quiet option is removed, gpg asks for the passphrase.
How do modify the git command VS Code uses?