Also show the manual backup cleanup info if storage format changes

dashboard/src/components/BackupDialog.vue

@@ -18,6 +18,7 @@ const formError = ref({});
 const busy = ref(false);
 const provider = ref('');
 const oldProvider = ref('');
+const oldFormat = ref('');
 const providerConfig = ref({
   limits: {},
   mountOptions: {},
@@ -161,6 +162,7 @@ defineExpose({
     oldProvider.value = result.provider;
     provider.value = result.provider;
     providerConfig.value = result;
+    oldFormat.value = result.format;
 
     // ensure we have all required child objects
     if (!providerConfig.value.mountOptions) providerConfig.value.mountOptions = {};
@@ -197,7 +199,7 @@ defineExpose({
         <fieldset :disabled="busy">
           <input style="display: none;" type="submit"/>
           <div class="error-label" v-show="formError.generic">{{ formError.generic }}</div>
-          <div class="warning-label" v-show="oldProvider !== provider">Backups in the old storage location have to be removed manually.</div>
+          <div class="warning-label" v-show="oldProvider !== provider || oldFormat !== providerConfig.format">{{ $t('backups.configureBackupStorage.formatChangeNote') }}</div>
 
           <BackupProviderForm v-model:provider="provider" v-model:provider-config="providerConfig" :form-error="formError"/>