Usual use case for short ternary is reading ACF field values and setting default if value is not set. Now it is not allowed.
$value = get_field('ploo') ? get_field('ploo') : 'moi;
could be written like
$value = get_field('ploo') ?: 'moi;
To allow short ternaries disable this: WordPress.PHP.DisallowShortTernary.Found