TYPO3v11: Deprecation: ContentObjectRenderer::parseFunc without any configuration

Upgrading from TYPO3 v10 to v11 brings following deprecation error:

TYPO3 Deprecation Notice: Invoking ContentObjectRenderer::parseFunc without any configuration will trigger an exception in TYPO3 v12.0 in /var/www/typo3/public/typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php line 3443

We used <f:format.html> in the backend preview sections of flux content elements - those triggered this notice.

Solution is to use <f:transform.html>, which works in the backend.

https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog/11.5/Feature-95176-IntroduceFtransformhtmlView-helper.html