Firstly try to use chainload to boot .efi files.

INSTALL/grub/grub.cfg

@@ -1445,21 +1445,21 @@ function efi_common_menuentry {
         vt_vlnk_dst="${vtoy_iso_part}${vt_chosen_path}"
     fi
     
-    vt_concat_efi_iso "${vt_vlnk_dst}" vtoy_iso_buf
-    
     ventoy_debug_pause
 
     ventoy_cli_console
     
-    unset vtoy_dotefi_retry
-    chainloader ${vtoy_path}/ventoy_${VTOY_EFI_ARCH}.efi memdisk env_param=${env_param} dotefi isoefi=on ${vtdebug_flag} mem:${vtoy_iso_buf_addr}:size:${vtoy_iso_buf_size}
+    #first try with chainload
+    set vtOldRoot=$root
+    set root=$vtoy_iso_part
+    chainloader "${vt_vlnk_dst}"
     boot
 
-    if [ -n "$vtoy_dotefi_retry" ]; then
-        unset vtoy_dotefi_retry
-        chainloader "${vt_vlnk_dst}"
+    #retry with isoboot
+    set root=$vtOldRoot
+    vt_concat_efi_iso "${vt_vlnk_dst}" vtoy_iso_buf    
+    chainloader ${vtoy_path}/ventoy_${VTOY_EFI_ARCH}.efi memdisk env_param=${env_param} dotefi isoefi=on ${vtdebug_flag} mem:${vtoy_iso_buf_addr}:size:${vtoy_iso_buf_size}
     boot    
-    fi
 
     ventoy_gui_console
 }