TYPO3 Core

You missed to descriped where you added the TSConfig setting. I assume
you tried to use PageTSConfig, but the point is that it must be user
based `UserTSConfig`.

You could add it for all users within a extension (sitepackage)
ext_localconf.php using

\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addUserTSConfig(<<<EOF
options.hideModules := addToList(web_typoscript_analyzer)
EOF
);

or setting it as TSConfig setting for a backend group ( be_groups ) or
backend user ( be_users )

options.hideModules := addToList(web_typoscript_analyzer)

I also flushed all caches, so not sure if it works without it. However,
using one of these variants worked for me (if the user is in the be group
or the user having that snippet if not all users have been disabled).

You are right Stefan, it works when you add it to the user TSconfig.

The migration path is counter-intuitive then as the code that was replaced used to be situated in the page TSconfig. Now the question is weather the Documentation or the implementation is correct here. Let us wait for what oli says.

Related:

https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-TSconfig/pull/463
https://github.com/TYPO3-Documentation/TYPO3CMS-Reference-TSconfig/pull/462

Patch set 2 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/83812

Patch set 1 for branch 12.4 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/83852