deprecate some fn commands

cmd/config/internal/commands/cmdxargs.go

@@ -60,6 +60,7 @@ $ kyaml cat pkg/ --function-config config.yaml --wrap-kind ResourceList | kyaml
 
 `,
 		RunE:               r.runE,
+		PreRunE:            r.preRunE,
 		SilenceUsage:       true,
 		FParseErrWhitelist: cobra.FParseErrWhitelist{UnknownFlags: true},
 		Args:               cobra.MinimumNArgs(1),
@@ -84,6 +85,12 @@ func XArgsCommand() *cobra.Command {
 	return GetXArgsRunner().Command
 }
 
+func (r *XArgsRunner) preRunE(_ *cobra.Command, _ []string) error {
+	_, err := fmt.Fprintln(os.Stderr, `Command "xargs" is deprecated, this will no longer be available in kustomize v5.
+See discussion in https://github.com/kubernetes-sigs/kustomize/issues/3953.`)
+	return err
+}
+
 func (r *XArgsRunner) runE(c *cobra.Command, _ []string) error {
 	if len(r.Args) == 0 {
 		r.Args = os.Args