magento2: Guest can't use Paypal Express in cart

I resolved it by adding a subscriber to cart section if initial value is undefined. If it is undefined it means localstorage is probably empty and sections did not finish loading yet. In magento/module-paypal/view/frontend/web/js/in-context/button.js:

initialize: function (config, element) {
            var cart = customerData.get('cart'),
                customer = customerData.get('customer');

            this._super();
            this.renderPayPalButtons(element);
            this.declinePayment = !customer().firstname && !cart().isGuestCheckoutAllowed;

            // BEGIN CHANGE
            if (cart().isGuestCheckoutAllowed === undefined) {
                cart.subscribe(function (updatedCart) {
                    this.declinePayment = !customer().firstname && !cart().isGuestCheckoutAllowed;
                    return updatedCart;
                }.bind(this));
            }
            // END CHANGE

            return this;
        }