Weird language behavior: First default language re-direct not working, now error

The CMS Questions
1

So I am building a fairly standard portfolio website that has two languages, en (default) and de.
On my localhost everything works fine the domain gets “re-directed” (not sure if thats the right wording here) to the domain.com/en and works as expected. On the server it just stayed on domain.com without automatically adding the /en. When I added it manually it did work, but this never happened before. Now suddenly it gives me an error:

Kirby\Cms\Page::urlForLanguage(): Argument #2 ($options) must be of type ?array, Kirby\Content\Field given, called in pathToWebsite/kirby/src/Cms/Page.php on line 1266

but debugger gives me the type error in line 1298

public function urlForLanguage(

Any ideas where to start fixing this? I don’t think I changed anything out of the ordinary. Hosting is on Strato, PHP is 8.3.31, Kirby is 5.5.2, website sits in a folder inside the root. I downloaded the whole site except for the content folder (since its large) and locally it does work…

2

Okay error seemed to be a mistake on my but it still does not redirect the domain to the /en default language…

3

Is the .htaccess file present on the server? is mod–redirect and.htaccess overwrites enabled?

4

.htaccess file is present and in default condition that it comes with in the plainkit, I tried RewriteBase / because with IONOS servers it often necessary but on this Strato server it did nothing.

EDIT: I put the page on my own Strato server and I do have the same problem, it is not turning the domain into the domain + the /en

EDITEDIT: I can’t believe how stupid I am, took me 10 hours to realize there was an empty index.html in the root folder, no idea how it got there but that was the problem all along. Sorry.