TYPO3 Core

When using a MM select with renderType selectMultipleSideBySide the left field shows the first element of the right field although that element is not saved.

TCA config:

...
        'config' => [
            'type' => 'select',
            'renderType' => 'selectMultipleSideBySide',
            'foreign_table' => 'tx_myextension_domain_model_mymodel',
            'MM' => 'tx_myextension_pages_mymodel_mm',
            'foreign_table_where' => 'ORDER BY title ASC'
        ]
...

Expected behaviour: show only the selected and saved items in left field
Actual behaviour: shows the selected and saved items plus the first of the not saved items from the right field

This happens in 9.5.15 but not in 9.5.14