Add to Cart Button does not work correctly the first time

My problem is that my Add to Cart button does not work correcty, when I use Incognito Browser and press add to cart the first time, nothing happens except the currently in shopping cart number changes to one.
When I press the button a second time, the pop-up for the shopping cart opens and it shows two in cart, when I refresh the shopping cart instead of pressing “add to cart” again it also shows one product in shopping cart.
I know why the shopping cart does not show, because of the error

So I know that obviously the cart does not update before the code is executed.
I changed a bit of code so I thought it might be my user code, even though I have not changed anything regarding the add to cart button, except some css.

I even went as far as just using a whole other theme completely from scratch to check if its my user code, but it still did not work.
I tried it on multiple devices and it never works the first time.
I am at a loss on what could trigger the error. I don’t use any apps that change the product pages or logic, just some cookie and order helper apps.
Can anyone help?
My website is: https://growrepublik.de/

This is probably an issue of theme code where it does not update automatically or instantly.

Please reach out via mail. I believe I can definitely take a look and come up with a solution for it.

I went over all my uninstalled apps, turns out I had “Selleasy in there”, I reinstalled it, turned it on and off manually and it worked, so probably the fact that I didnt turn off the app in the Theme Editor before I uninstalled it somehow fucked up the workflow.