Yes it is only showing once in your store currently. try adding this instead to theme.css:
button.product-item__hoverless-quick-view-button.btn
{ bottom: 0;
right: 0;
padding: 8px;
padding: var(--spacing-2);
min-width: 0;
min-height: 0;
z-index: 2;
}
Otherwise you can try going to Themes> Customize> Collection Template> Product Grid> Custom CSS
then add the code from my above and click Save.
If this does not work let me know I can request access to the store and do it for you. Thanks!
@biznazz101