MasterPress 1.3.1 is a compatibility release for PHP 8 and WordPress 5.7. It still remains backwards compatible with older PHP versions.
MEOW_FieldSetCollection :: update()
Updates the database with with any changes made by any methods that can update the field set collection or the field sets / field within. Note that because of the way MasterPress stores values, this method will be called by the update methods of all contained fields and field sets.