This is very confusing as seen in #12974 or #12906. My suggestion would be "legacy."
gulp.task(
  "image_decoders",
  gulp.series("buildnumber", function () {
    console.log();
    console.log("### Creating image decoders");
    var defines = builder.merge(DEFINES, {
      GENERIC: true,
      IMAGE_DECODERS: true,
    });
    return createImageDecodersBundle(defines).pipe(
      gulp.dest(IMAGE_DECODERS_DIR)
    );
  })
);
gulp.task(
  "image_decoders-es5",
  gulp.series("buildnumber", function () {
    console.log();
    console.log("### Creating (ES5) image decoders");
    var defines = builder.merge(DEFINES, {
      GENERIC: true,
      IMAGE_DECODERS: true,
      SKIP_BABEL: false,
    });
    return createImageDecodersBundle(defines).pipe(
      gulp.dest(IMAGE_DECODERS_ES5_DIR)
    );
  })
);
function buildMinified(defines, dir) {