Working with the wp_kses_allowed_html

Originally posted by @CreativeDive in https://github.com/AdvancedCustomFields/acf/issues/500#issuecomment-844809750

add_filter( 'wp_kses_allowed_html', function( $tags, $context ) {
        
	if( 'post' !== $context ) {
		return $tags;	
	}

	global $tags;

	// allowed attributes
	$allowed_atts = array(
		'class' => array(),
		'id' => array(),
		'style' => array(),
		'isolation' => array (),
		'align' => array(),
		'src' => array(),
		'alt' => array(),
		'title' => array(),
		'href' => array(),
		'rel' => array(),
		'rev' => array(),
		'target' => array(),
		'name' => array(),
		'tabindex' => array(),
		'for' => array(),
		'width' => array(),
		'height' => array(),
		'data' => array(),
		'data-parent' => array(),
		'data-toggle' => array(),
		'data-id' => array(),
		'srcset' => array(),
		'loading' => array(),
		'sizes' => array(),
		'itemprop' => array(),
		'frameborder' => array(),
		'allowfullscreen' => array(),
		'allowtransparency' => array(),
		'd' => array(),
		'version' => array(),
		'viewbox' => array(), // <= Must be lower case!
		'xmlns' => array(),
		'xmlns:xlink' => array(),
		'x' => array(),
		'y' => array(),
		'xml:space' => array(),
		'fill' => array(),
		'fill-opacity' => array(),
		'opacity' => array(),
		'points' => array(),
		'preserveaspectratio' => array(), // <= Must be lower case!
		'clippathunits' => array(), // <= Must be lower case!
		'transform' => array(),
		'role' => array(),
		'focusable' => array(),
		'aria-hidden' => array(),
	);

	// allowed tags
	$tags['iframe'] = $allowed_atts;
	$tags['style'] = $allowed_atts;
	$tags['noscript'] = $allowed_atts;
	$tags['div'] = $allowed_atts;
	$tags['img'] = $allowed_atts;
	$tags['svg'] = $allowed_atts;
	$tags['defs'] = $allowed_atts;
	$tags['clippath'] = $allowed_atts;
	$tags['foreignobject'] = $allowed_atts;
	$tags['g'] = $allowed_atts;
	$tags['path'] = $allowed_atts;
	$tags['rect'] = $allowed_atts;
	$tags['polygon'] = $allowed_atts;
	$tags['strong'] = $allowed_atts;
	$tags['small'] = $allowed_atts;
	$tags['caption'] = $allowed_atts;
	$tags['table'] = $allowed_atts;
	$tags['tbody'] = $allowed_atts;
	$tags['thead'] = $allowed_atts;
	$tags['tfoot'] = $allowed_atts;
	$tags['th'] = $allowed_atts;
	$tags['tr'] = $allowed_atts;
	$tags['td'] = $allowed_atts;
	$tags['form'] = $allowed_atts;
	$tags['fieldset'] = $allowed_atts;
	$tags['legend'] = $allowed_atts;
	$tags['label'] = $allowed_atts;
	$tags['input'] = $allowed_atts;
	$tags['button'] = $allowed_atts;
	$tags['select'] = $allowed_atts;
	$tags['datalist'] = $allowed_atts;
	$tags['optgroup'] = $allowed_atts;
	$tags['option'] = $allowed_atts;
	$tags['textarea'] = $allowed_atts;
	$tags['keygen'] = $allowed_atts;
	$tags['output'] = $allowed_atts;
	$tags['progress'] = $allowed_atts;
	$tags['meter'] = $allowed_atts;
	$tags['span'] = $allowed_atts;
	$tags['abbr'] = $allowed_atts;
	$tags['acronym'] = $allowed_atts;
	$tags['mark'] = $allowed_atts;
	$tags['address'] = $allowed_atts;
	$tags['files'] = $allowed_atts;
	$tags['blockquote'] = $allowed_atts;
	$tags['figure'] = $allowed_atts;
	$tags['figcaption'] = $allowed_atts;
	$tags['time'] = $allowed_atts;
	$tags['data'] = $allowed_atts;
	$tags['cite'] = $allowed_atts;
	$tags['q'] = $allowed_atts;
	$tags['code'] = $allowed_atts;
	$tags['pre'] = $allowed_atts;
	$tags['header'] = $allowed_atts;
	$tags['main'] = $allowed_atts;
	$tags['nav'] = $allowed_atts;
	$tags['section'] = $allowed_atts;
	$tags['article'] = $allowed_atts;
	$tags['aside'] = $allowed_atts;
	$tags['footer'] = $allowed_atts;
	$tags['embed'] = $allowed_atts;
	$tags['object'] = $allowed_atts;
	$tags['param'] = $allowed_atts;
	$tags['video'] = $allowed_atts;
	$tags['audio'] = $allowed_atts;
	$tags['source'] = $allowed_atts;
	$tags['track'] = $allowed_atts;
	$tags['canvas'] = $allowed_atts;
	$tags['map'] = $allowed_atts;
	$tags['area'] = $allowed_atts;
	$tags['math'] = $allowed_atts;
	$tags['h1'] = $allowed_atts;
	$tags['h2'] = $allowed_atts;
	$tags['h3'] = $allowed_atts;
	$tags['h4'] = $allowed_atts;
	$tags['h5'] = $allowed_atts;
	$tags['h6'] = $allowed_atts;
	$tags['ol'] = $allowed_atts;
	$tags['ul'] = $allowed_atts;
	$tags['li'] = $allowed_atts;
	$tags['sup'] = $allowed_atts;
	$tags['sub'] = $allowed_atts;
	$tags['del'] = $allowed_atts;
	$tags['ins'] = $allowed_atts;
	$tags['dl'] = $allowed_atts;
	$tags['dt'] = $allowed_atts;
	$tags['dd'] = $allowed_atts;
	$tags['em'] = $allowed_atts;
	$tags['hr'] = $allowed_atts;
	$tags['br'] = $allowed_atts;
	$tags['wbr'] = $allowed_atts;
	$tags['p'] = $allowed_atts;
	$tags['a'] = $allowed_atts;
	$tags['b'] = $allowed_atts;
	$tags['i'] = $allowed_atts;
	$tags['u'] = $allowed_atts;
	$tags['s'] = $allowed_atts;
	$tags['extended_valid_elements'] = 'style';

	return $tags;
        
}, 10, 2 );

The issue only provides a wp_kses_allowed_html filter snippet and does not name a repository file, test, or expected change. Start by locating the filter integration point in the WordPress-related code, then clarify the intended behavior and how completion would be verified.