TYPO3 Core

I have a form field whose values comes from a list of subscribed classes for some roles.

The flexform TCA for this form field looks like that:

<providers>
    <TCEforms>
        <label>LLL:EXT:my_ext/Resources/Private/Language/locallang.xlf:flexform.sheets.general.providers</label>
        <config>
            <type>select</type>
            <itemsProcFunc>Vendor\MyExt\Flexform\Helper-&gt;renderProviderList</itemsProcFunc>
            <maxitems>100</maxitems>
            <size>4</size>
        </config>
    </TCEforms>
</providers>

The computed items list looks like:

[
    [ 'First provider', 'Vendor\\MyExt\\FirstProvider' ],
    [ 'Second provider', 'Vendor\\MyExt\\SecondProvider' ]
]

Manipulating the form element does not work well.

The issue is removing an element from the selected box is not working. After step by step debugging, it looks like the value $(this).attr('value') needs selector string escaping on line 569 of EXT:backend/Resources/Public/JavaScript/FormEngine.js.

Also affect 8 LTS. The affected code portion is the same. Only one line down.