TYPO3 Core

Bug:
When I open a content element that uses flux.sections, there are no titles in the individual "tabs". If a single tab is opened and closed once, a title is visible in that tab (content of the tab).
This problem seems to be browser dependent. I could only see this problem in Mozilla Firefox, in Google Chrome it work properly.

Environment:
TYPO3: 11.5.14
Flux: 9.6.1

Tested Browser:
Mozilla Firefox 91.12.0esr (64-Bit) (on Windows)
Mozilla Firefox 103.0 (64-Bit) (on Mac)

Screenshot of the Problem:

Flux Configuration:

<f:section name="Configuration">
<flux:form options="{group: 'FCE', icon: 'EXT:frp_fce/Resources/Public/Thumbnails/module_contentslider.png'}" id="contentslider">
    <flux:form.sheet name="slider">
        <flux:form.section name="slides" label="slides">
            <flux:form.object name="default">
                <flux:field.input name="caption" maxCharacters="55" required="1"/>
                <flux:field.input name="title" maxCharacters="30" required="1"/>
                <flux:field.input name="subtitle" maxCharacters="55" required="1"/>
                <flux:field name="link" label="link" type="input" config="{
                                    renderType: 'inputLink'
                            }" />
                            <flux:field.input name="linktext" maxCharacters="55" required="1"/>
                            <flux:field type="group" 
                                    name="image" 
                                    label="Images" 
                                    config="{
                                        type: 'group',
                                        internal_type: 'db',
                                        allowed: 'sys_file',
                                        size: '1',
                                        minitems: 0,
                                        maxitems: 1,
                                        show_tumbs: 1,
                                    appearance: {
                                            elementBrowserType: 'file',
                                            elementBrowserAllowed: 'jpg,jpeg,png,gif'
                                }}" />
                </flux:form.object>
            </flux:form.section>
        </flux:form.sheet>
    </flux:form>
</f:section>

for better readability, flux config also visible in a gist:
https://gist.github.com/frpuser/6ab728bfc12ddbf37e7c83d4180370fe

We created a new issue at the flux github but got the answer that this is not a flux related problem:
"Sorry, but you have to report this to the TYPO3 core bug tracker, https://forge.typo3.org. The problem is not caused by Flux and cannot be fixed in Flux - any implementation of a FlexForm with section+sectionobject (and possibly even root level TCA fields of type inline, I've not tested this) also without Flux would be similarly affected."