Deprecation: #63453 - Deprecate renderMode attribute of FlashMessagesViewHelper

See Issue #63453

Description

Deprecated renderMode in favor of a flexible deferred rendering of flash messages in the Fluid template. This means that flash messages should no longer contain HTML, but the HTML output can and should be adjusted in the Fluid template.

Impact

Using renderMode on FlashMessage output will throw a deprecation warning.

Affected Installations

All instances using the renderMode attribute in FlashMessage output.

Migration

Adjust flash messages to contain only plain text and remove the renderMode attribute in the output Templates.

<f:flashMessages as="flashMessages">
        <ul class="typo3-flashMessages">
                <f:for each="{flashMessages}" as="flashMessage">
                        <li class="alert {flashMessage.class}">
                                <h4>{flashMessage.title}</h4>
                                {flashMessage.message}
                        </li>
                </f:for>
        </ul>
</f:flashMessages>