@paypal/react-paypal-js throwing contradictory errors: "sdk is already loaded" and "window.paypal.Buttons is undefined"

I am using the @paypal/react-paypal-js library to integrate Paypal Buttons into my app like this:

 import { PayPalScriptProvider, PayPalButtons } from "@paypal/react-paypal-js";

export default function App() {
    return (
        <PayPalScriptProvider options={{ "client-id": "test" }}>
            <PayPalButtons style={{ layout: "horizontal" }} />
        </PayPalScriptProvider>
    );
}

When testing, the page freezes, and the console says:

Uncaught Error: Attempted to load sdk version 5.0.263 on page, but window.paypal at version undefined already loaded.

To load this sdk alongside the existing version, please specify a different namespace in the script tag, e.g. <script src="https://www.paypal.com/sdk/js?client-id=CLIENT_ID" data-namespace="paypal_sdk"></script>, then use the paypal_sdk namespace in place of paypal in your code.
    
Error: Unable to render <PayPalButtons /> because window.paypal.Buttons is undefined.
    

How is this possible? I checked multiple times that there is no script tag including the SDK already.

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