SharePoint Online JavaScript creates folder instead of document set

Hello! We have a SharePoint Online system with 4 custom new forms created with Html/JavaScript. These forms used to create document sets and worked very well for a year (the forms are for different document libraries on different subsites). Starting yesterday, they suddenly creating folders instead of document sets.

Interesting, but the folders have the correct content type, not Folder content type. We checked and the content type id's havent changed. Here is the JS code:

function createDocset() {
var ctx = new SP.ClientContext(_spPageContextInfo.webServerRelativeUrl);
var web = ctx.get_web();
var list = web.get_lists().getByTitle('dummy');
SP.SOD.executeFunc('sp.js', 'SP.ClientContext'); 
newDocSetName = 'dummy';
var docSetContentTypeID = '0x0120D52000A5EFC11713588E41B8E1058A74F53AF2';
currentDate = new Date().getFullYear();
ctx.load(list);
folderUrl = "dummy" + currentDate;
var folder = web.getFolderByServerRelativeUrl(folderUrl);
ctx.load(folder);   
var docsetContentType = web.get_contentTypes().getById(docSetContentTypeID);
ctx.load(docsetContentType);
ctx.executeQueryAsync(function () {
    console.log("Content-type: " + docsetContentType);
isCreated = SP.DocumentSet.DocumentSet.create(ctx, folder, newDocSetName, docsetContentType.get_id());
console.log("Created: ", isCreated);
ctx.executeQueryAsync(SuccessHandler('Document Set creation successful'), FailureHandler("Document Set creation failed"));
}, FailureHandler("Folder loading failed"));
ctx.add_requestSucceeded(function () {
});
ctx.add_requestFailed(function (sender, args) {
alert('Request failed: ' + args.get_message());
});
// Failure Message Handler
function FailureHandler(message) {
    return function (sender, args) {
        alert(message + ": " + args.get_message());
    }
}
// Success Message Handler
function SuccessHandler(message) {
    return function () {
        setDocset();
    }
}}

There are 2 custom document set content types in this library. The forms using their content type id's. The id's havent changed.

Thank you very much!