Important: #102551 - FlexForm section _TOGGLE control removed

Description

Historically, FlexForms store their section collapsing state within the flex structure in the database, having the impact that the state is reflected to every backend user. The control field _TOGGLE responsible for this behavior is now removed, the state is persisted in the backend user's local storage instead.

It is highly recommended to clean existing FlexForm records by invoking the following command:

bin/typo3 cleanup:flexforms

If this is not possible, a scheduler task of type Execute console commands with the command cleanup:flexforms: Clean up database FlexForm fields that do not match the chosen data structure. may be set up and used.