Try adding fling gesture handler

src/screens/ImagesViewer.tsx

@@ -18,7 +18,12 @@ import {
   ViewToken
 } from 'react-native'
 import FlashMessage from 'react-native-flash-message'
-import { LongPressGestureHandler } from 'react-native-gesture-handler'
+import {
+  Directions,
+  FlingGestureHandler,
+  LongPressGestureHandler,
+  State
+} from 'react-native-gesture-handler'
 import { Zoom, createZoomListComponent } from 'react-native-reanimated-zoom'
 import { SafeAreaProvider, useSafeAreaInsets } from 'react-native-safe-area-context'
 import saveImage from './ImageViewer/save'
@@ -93,6 +98,8 @@ const ScreenImagesViewer = ({
     }) => {
       const screenRatio = SCREEN_WIDTH / SCREEN_HEIGHT
       const imageRatio = item.width && item.height ? item.width / item.height : 1
+      const imageWidth = item.width || 100
+      const imageHeight = item.height || 100
 
       const maxWidthScale = item.width ? (item.width / SCREEN_WIDTH / PixelRatio.get()) * 4 : 0
       const maxHeightScale = item.height ? (item.height / SCREEN_WIDTH / PixelRatio.get()) * 4 : 0
@@ -116,9 +123,13 @@ const ScreenImagesViewer = ({
                 blurhash={item.blurhash}
                 dimension={{
                   width:
-                    screenRatio > imageRatio ? (item.height || 100) / screenRatio : SCREEN_WIDTH,
+                    screenRatio > imageRatio
+                      ? (SCREEN_HEIGHT / imageHeight) * imageWidth
+                      : SCREEN_WIDTH,
                   height:
-                    screenRatio > imageRatio ? SCREEN_HEIGHT : (item.width || 100) * screenRatio
+                    screenRatio > imageRatio
+                      ? SCREEN_HEIGHT
+                      : (SCREEN_WIDTH / imageWidth) * imageHeight
                 }}
               />
             </View>
@@ -161,6 +172,11 @@ const ScreenImagesViewer = ({
           onPress={onPress}
         />
       </View>
+      <FlingGestureHandler
+        direction={Directions.DOWN}
+        numberOfPointers={1}
+        onEnded={() => navigation.goBack()}
+      >
         <LongPressGestureHandler
           onEnded={() => {
             analytics('imageviewer_more_press')
@@ -203,7 +219,6 @@ const ScreenImagesViewer = ({
           }}
         >
           <ZoomFlatList
-          ref={listRef}
             data={imageUrls}
             pagingEnabled
             horizontal
@@ -221,6 +236,7 @@ const ScreenImagesViewer = ({
             })}
           />
         </LongPressGestureHandler>
+      </FlingGestureHandler>
       <Message ref={messageRef} />
     </SafeAreaProvider>
   )