Additional classes `undefined` after saving post in Gutenberg

After about an hour of trial and error, I found that the outmost <Fragment> was the culprit. But I still can’t figure out why! Replacing it with <div> fixed it.

So the code looks like this now:

    edit: (props) => {
        const {attributes, setAttributes} = props;
        const headingBgOverlay = Util.getBgOverlay(attributes, 'heading');
        const bodyBgOverlay = Util.getBgOverlay(attributes, 'body');

        useEffect(() => {
            setAttributes({blockId: Util.guidGenerator()});
        }, []);

        useEffect(() => {
            console.log(props)
            console.log(props.className)
            console.log(attributes.className)
            setAttributes({headingBgOverlay});
            setAttributes({bodyBgOverlay});
        }, [attributes]);
        return (
                <div>
                    <style>
                        {listIconCss(attributes)}
                    </style>
                    <div className={"atbs atbs-pricing-table " + props.className}
                         id={'atbs-pricing-table-' + attributes.blockId}>
                        <div className="plan"
                             style={{...planCss(attributes)}}>
                            <div className="head" style={{...titleCss(attributes)}}>
                                <RichText style={{...titleTypographyCss(attributes)}} tagName="h2" className={'m-0'}
                                          value={attributes.title}
                                          onChange={(title) => setAttributes({title})}
                                          placeholder={__('Plan name', 'attire-blocks')}/>
                            </div>
                            <div className="atbs_pricing_table_body">
                                <RichText
                                    style={{...descrCss(attributes)}}
                                    className={'description'} tagName="p" value={attributes.description}
                                    onChange={(description) => setAttributes({description})}
                                    placeholder={__('Description...', 'attire-blocks')}/>
                                <div className="price" style={{...priceCss(attributes)}}>
                                    <RichText style={{fontSize: (attributes.priceFontSize / 2) + 'px'}}
                                              className={'symbol'}
                                              tagName="span" value={attributes.symbol}
                                              onChange={(symbol) => setAttributes({symbol})}
                                              placeholder={__('$')}/>
                                    <RichText className={'amount'}
                                              tagName="span" value={attributes.price}
                                              onChange={(price) => setAttributes({price})}
                                              placeholder={__('99.99')}/>

                                    {attributes.recurring && <RichText
                                        style={{fontSize: `${attributes.descrFontSize}${attributes.descrFontSizeUnit}`}}
                                        tagName="span" value={attributes.recurringTime}
                                        className="recurring"
                                        onChange={(value) => setAttributes({recurringTime: value})}
                                        placeholder={__('/month', 'attire-blocks')}/>}

                                </div>
                                {attributes.showFeatures && <RichText
                                    style={{...listCss(attributes)}}
                                    multiline="li"
                                    tagName="ul"
                                    className="features"
                                    onChange={(nextValues) => setAttributes({features: nextValues})}
                                    value={attributes.features}
                                    placeholder={__('Write list…', 'attire-blocks')}
                                />}

                                <InnerBlocks allowedBlocks={['attire-blocks/buttons']}
                                             template={[['attire-blocks/buttons', {
                                                 buttonAlignment: 'center'
                                             }]]}
                                             templateLock="all"/>
                            </div>
                        </div>
                    </div>
                </div>
        );
    },
    save: ({attributes, className}) => {
        //const {attributes} = props;
        return (
            <div>
                <style>
                    {listIconCss(attributes)}
                </style>
                <div className={"atbs atbs-pricing-table " + className}
                     id={'atbs-pricing-table-' + attributes.blockId}>
                    <div className="plan"
                         style={{...planCss(attributes)}}>
                        {attributes.title &&
                        <div className="head" style={{...titleCss(attributes)}}>
                            <RichText.Content style={{...titleTypographyCss(attributes)}} tagName="h2" className={'m-0'}
                                              value={attributes.title}/>
                        </div>}
                        <div className="atbs_pricing_table_body">
                            {attributes.description &&
                            <RichText.Content
                                style={{...descrCss(attributes)}}
                                className={'description'} tagName="p" value={attributes.description}/>}
                            <div className="price" style={{...priceCss(attributes)}}>
                                <RichText.Content style={{fontSize: (attributes.priceFontSize / 2) + 'px'}}
                                                  className={'symbol'} tagName="span" value={attributes.symbol}/>
                                <RichText.Content
                                    style={{
                                        color: attributes.bodyTextColor,
                                        fontSize: (attributes.priceFontSize) + 'px'
                                    }}
                                    className={'amount'}
                                    tagName="span" value={attributes.price}/>
                                {attributes.recurring && <RichText.Content
                                    style={{fontSize: `${attributes.descrFontSize}${attributes.descrFontSizeUnit}`}}
                                    className="recurring"
                                    tagName="span" value={attributes.recurringTime}/>}
                            </div>
                        </div>
                        {attributes.showFeatures && <RichText.Content
                            style={{...listCss(attributes)}}
                            className={'features'}
                            tagName="ul" value={attributes.features}/>}
                        <InnerBlocks.Content/>
                    </div>
                </div>
            </div>
        );
    }
});