the issue seemed to be linked to the use of table instead of div

Flask/templates/vnc_post.html

@@ -10,23 +10,16 @@
         <script src="{{ url_for('static', filename='node_modules/xterm/lib/xterm.js') }}"></script>
         <script src="{{ url_for('static', filename='node_modules/xterm-addon-fit/lib/xterm-addon-fit.js') }}"></script>
 
-        <table>
+        <div>
-            <tr>
+
-                <td width="20%" height="90%">
+            <div id="console" style="height: 100%; width: 20%; float:left;"></div>
-                    <div id="console"></div>
+
-                </td>
+            <div style="width: 80%; float:left;">
-                <td width="80%">
                 <iframe src="/novnc/vnc.html?resize=scale&path=novnc/websockify&autoconnect=true&view_only"
                         width="100%" height="100%" frameborder="0"></iframe>
-                </td>
+            </div>
-            </tr>
+        </div>
-        </table>
 
-
-        <script>
-
-
-        </script>
         <script>
             var term = new Terminal();
             const fitAddon = new FitAddon.FitAddon();

version

@@ -1 +1 @@
-v6.8.30
+v6.8.31