Hi,

1) Open your event template with the builder.

2) Insert "Custom JS" element in the template. You can place it somewhere at the bottom.

3) Open the Custom JS element settings by clicking on the cogwheel icon.

4) In the JavaScript textarea place the following javascript code:

(function () {

    const userId = STEC_VARIABLES?.current_user?.data?.id;

    if (!userId) {
        
        const elementToHide = document.querySelector('.stec-event-share-and-export-subscribe');

        if (elementToHide) {
            elementToHide.style.display = 'none';
        }
    }

})();

You can do it via the template builder.

Open your template.

Click on the Row Section that wraps the Comments:

Click on the cogwheel button to enter its settings.

In the Conditions selector add: "Logged-in":

Are you sure it's not old cache on your mobile device?

The elements share same class name both for desktop and mobile. It doesn't make sense to show on one and be hidden on another.

Where can I see this issue?

Try different approach. 

Remove the custom js code I've sent you earlier and instead place two row sections with logged-in and not logged-in conditions. I'm attaching you a video of what I mean.