Dear Maintainer,

These files I have built from scratch should be installed to the listed files. Not sure where else to suggest this feature though.
-- /usr/share/zsh/vendor-completions/_keepassxc
#compdef keepassxc

_arguments \
    {-h,--help}'[Displays help on commandline options.]' \
    --help-all'[Displays help including Qt specific options.]' \
    {-v,--version}'[Displays version information.]' \
    --config'[path to a custom config file]':'<config>':_files \
    --localconfig'[path to a custom local config file]':'<localconfig>':_files \
    --lock'[lock all open databases]' \
    --keyfile'[key file of the database]':'<keyfile>':_files \
    --pw-stdin'[read password of the database from stdin]' \
    --debug-info'[Displays debugging information.]' \
    --allow-screencapture'[allows screenshots and app recording (Windows/macOS)]' \
    --minimized'[start minimized to the system tray]' \
    '*:filename(s):_files'
-- end /usr/share/zsh/vendor-completions/_keepassxc

Updated to support single letter stacking.
Please see new files listed below:
-- /usr/share/zsh/vendor-completions/_keepassxc
#compdef keepassxc
_arguments -C -S -s \
    '(- 1 *)'{-h,--help}'[Displays help on commandline options.]' \
    '(- 1 *)'--help-all'[Displays help including Qt specific options.]' \
    '(- 1 *)'{-v,--version}'[Displays version information.]' \
    --config='[path to a custom config file]':'<config>':_files \
    --localconfig='[path to a custom local config file]':'<localconfig>':_files \
    --lock'[lock all open databases]' \
    --keyfile='[key file of the database]':'<keyfile>':_files \
    --pw-stdin'[read password of the database from stdin]' \
    '(- 1 *)'--debug-info'[Displays debugging information.]' \
    --allow-screencapture'[allows screenshots and app recording (Windows/macOS)]' \
    --minimized'[start minimized to the system tray]' \
    '*:filename(s):_files'
-- end /usr/share/zsh/vendor-completions/_keepassxc