How to collect Okta group membership information from a browser to figure manually assigned users vs. assigned by a rule (make sure you are not using new Group UX feature enabled)

script.js

function loop(i) {
	setTimeout(() => {
		fetch('https://' + domain + '/admin/users/search?sEcho=1&iColumns=9&sColumns=user.id%2Cuser.fullName%2Cuser.lastName%2Cuser.email%2Cuser.login%2Cstatus.statusLabel%2Cstatus.loginStatus%2Cstatus.statusCode%2CmanagedBy.rules&iDisplayStart=' + i +'&iDisplayLength=100&sSearch=&bRegex=false&sSearch_0=&bRegex_0=false&bSearchable_0=true&sSearch_1=&bRegex_1=false&bSearchable_1=true&sSearch_2=&bRegex_2=false&bSearchable_2=true&sSearch_3=&bRegex_3=false&bSearchable_3=true&sSearch_4=&bRegex_4=false&bSearchable_4=true&sSearch_5=&bRegex_5=false&bSearchable_5=true&sSearch_6=&bRegex_6=false&bSearchable_6=true&sSearch_7=&bRegex_7=false&bSearchable_7=true&sSearch_8=&bRegex_8=false&bSearchable_8=true&iSortingCols=1&iSortCol_0=1&sSortDir_0=asc&bSortable_0=true&bSortable_1=true&bSortable_2=true&bSortable_3=true&bSortable_4=true&bSortable_5=false&bSortable_6=true&bSortable_7=true&bSortable_8=false&orderBy=lastName&sortDirection=asc&groupId=' + grpId)
		.then(resp => resp.text())
		.then(data => {
			var json = JSON.parse(data.substring(11));	// 11 is a number of first symbols to remove from the result, 
									// as it's always "while(1){};"
			console.log(json.aaData);			// just for visual progress tracking
			aaData = aaData.concat(json.aaData);
			if (i < upper)
				loop(i + 100)
		})
	}, 10000)
}

var domain = 'your_domain.okta.com';
var grpId = 'target_group_guid'		// group Okta GUID
var timeout = 10000;			//timeout between calls to preserve rate limit
var upper = 2000;			// as calls are for 100 users per call, upper limit is rounded to the lowest 
					// for 2054 it's 2000, for example

var i = 0;
var aaData = [];
loop(i)

After the script finished its work, the result will be in aaData and you can do whatever you need with it. Something like

aaData.filter(el => Object.keys(el[8]).length == 0).map(el => {console.log(el[0])})

will produce GUIDs of all manually assigned users