In this project I gradually updated a small site with a little more than a dozen TYPO3 pages from TYPO3 version 9.5 under PHP 7.4 to TYPO3 version 11.5.x under PHP 8.1.
This environment had 2 local extensions, one of which was Gridelements. Since Gridelements is only supported up to TYPO3 10, this extension has been replaced by containers.
The template was adapted to the TYPO3 11 version without any changes. The template was integrated via TypoScript and Fluid Styled Content and was not encapsulated in a TYPO3 extension, but was stored below the fileadmin folder.
All necessary TypoScript changes have also been made.