A Global UI Script workaround for https://hi.service-now.com/kb_view.do?sysparm_article=KB0551949.

ServiceNow Geneva iFrame Resize UI Script.js

(function() {
	var essUrl = 'ess';
	var pollingDelay = 250;
	var prevHeight;
	var src = '';
	var blacklist = [];
	
	/**
 	* Executes the proper calculation strategy and returns the internal height of the iframe.  You should edit this function if you find strategies that are not accounted for
 	* @function getHeight
 	*/
	var getHeight = function() {
		if (iframePageIs('com.glideapp.servicecatalog_checkout_view_v2.do')) {
			return getTotalHeight([
			'body > .outputmsg_div',
			'body > table:nth-of-type(1)',
			'#sc_order_status_intro_text',
			'#sc_cart_view',
			'.catalog_button_container'
			], 0);
		}
		else if (iframePageIs('com.glideapp.servicecatalog_category_view.do')) {
			return getTotalHeight([
			'body'
			], 0);
		}
		else if (iframePageIs('com.glideapp.servicecatalog_cat_item_view.do')) {
			// resize catalog forms
			return getTotalHeight([
			'body > .outputmsg_div',
			'body > table:nth-of-type(1)',
			'#item_table',
			'body > table:nth-of-type(3)'
			], 100);
		}
		else if (iframePageIs('catalog_home.do')) {
			return getTotalHeight([
			'body > .outputmsg_div',
			'body > table:nth-of-type(1)',
			'#homepage_grid'
			]);
		}
		else if (iframePageIs('$knowledge.do')) {
			// Knowledge v3 UI
			if ($('gsft_main').contentWindow.$j('body')[0].style.overflow != 'hidden') {
				$('gsft_main').contentWindow.$j('body')[0].style.overflow = 'hidden';
			}
			
			// Shrink iframe when the src changes to force a recalculation
			if (src != $('gsft_main').contentWindow.location.href) {
				src = $('gsft_main').contentWindow.location.href;
				return 400;
			}
			
			return getTotalHeight(['.application'], 100);
		}
		else if (iframePageIs('kb_view.do')) {
			return getTotalHeight([
			'body > .outputmsg_div',
			'body > .navbar',
			'.kb-view-content-wrapper',
			'.snc-article-header-author',
			'.snc-article-footer-section',
			'.snc-article-footer'
			], 100);
		}
		else if (iframePageIs('assessment_take2.do')) {
			// Resize Assessments
			return getTotalHeight([
			'form'
			], 100);
		}
		else if (iframePageIs('slushbucket.do')) {
			// Resize Form Edit page
			return getTotalHeight([
			'body > .outputmsg_div',
			'.section_header_div_no_scroll',
			'#slushbucket_body'
			], 100);
		}
		else if (iframePageIs('$pwd')) {
			// Password Reset Pages, may need to adjust if statement for configured public URLs
			return getTotalHeight([
			'body'
			], 100);
		}
		else if (iframePageIs('cms_admin_iframe.do')) {
			return getTotalHeight([
			'body'
			], 0);
		}
		else if (iframePageIs('expert_shell.do')){
			//Wizards
			return getTotalHeight([
			'body'
			], 200);
		}
		else {
			// resize default
			return getTotalHeight([
			'body > .outputmsg_div',
			'.section_header_div_no_scroll',
			'.form_body',
			'.navbar-fixed-bottom',
			'.tabs2_spacer',
			'.tabs2_list'
			], 100);
		}
	};
	
	/**
 	* @function getTotalHeight
 	* @param {array} divs - Array of CSS selectors that identify the div's whose height should be added in the calculation
 	* @param {int} modifier - Number of additional pixels to add as a modifier
 	*/
	var getTotalHeight = function(divs, modifier) {
		var h = 0;
		
		$j.each(divs, function(ix, val) {
			h = h + $('gsft_main').contentWindow.$j(val).height();
		});
		
		return h + modifier;
	};
	
	/**
 	* Determines if the url contains the given fragment
 	* @function iframePageIs
 	* @param {string} urlFragment - String to search for in the iframe url
 	*
 	*/
	var iframePageIs = function(urlFragment) {
		return ($('gsft_main').contentWindow.location.href.indexOf(urlFragment) != -1);
	};
	
	/**
 	* A recursive polling function that gets the internal height of the iframe and resizes the it accordingly.
 	* @function resizeIframeFix
 	*/
	var resizeIframeFix = function() {
		setTimeout(function() {
			var curHeight;
			var i;
			
			for (i = 0; i < blacklist.length; i++) {
				if (iframePageIs(blacklist[i])) {
					return;
				}
			}
			
			if ($j && $('gsft_main') && $('gsft_main').contentWindow.$j) {
				curHeight = getHeight();
				
				if (prevHeight != curHeight) {
					$j('#gsft_main').height(curHeight);
					prevHeight = getHeight();
				}
			}
			
			resizeIframeFix();
		}, pollingDelay);
	};
	
	// Iniaite polling loop if we are on a top level CMS page
	if (top == window && window.location.href.indexOf(essUrl) != -1) {
		addAfterPageLoadedEvent(function() {
			// if resizable iframe exists
			if ($('gsft_main')) {
				resizeIframeFix();
			}
		});
	}
})();

Originally I had two strategies, one that would run inside the iframe and another for Knowledge V3 that would calculate from outside the iframe. I have merged these into a single strategy for simplicity sake. Knowledge V3 UI would not work with the inside strategy so I chose the outside strategy. Basically, the polling loop:

1. Checks the URL of the iframe's document
2. Chooses the right calculation strategy for the URL
3. Calculates the height of the iframe's document
4. Sets the iframe height
5. Recalculates the iframe document's height for a check in the next loop to prevent infinite growth of a page (Knowledge v3 in particular grows without this check, kudos to ServiceNow for helping me solve this part)
6. Executes the polling loop function causing the loop to run again after a timeout

Added support for resizing the iframe for Assessment Surveys

Added support for Form and List configuring from the portal

Added support for Password reset forms

Added support for Catalog Category page (com.glideapp.servicecatalog_category_view.do) with help from Shannon Burns

Added support for kb_view.do and fixed some bugs with the outputmsg_div

Added support for a blacklist of URLs and for the CMS Admin Iframe with help from Adam Thomson

Added support for Wizards courtesy of Ben Collyer. Also confirmed that the script is still fully functional in Jakarta.