CloudFront with Lambda@Edge results in CORS problem

Question

I've configured S3 with access only through CloudFront and protected with lambda executed on Viewer request. The problem is that I'm not able to access the files from SPA because of a failing preflight call.

When I removed the lambda function everything is starting to work. This is surprising to me because lambda is not modifying the request at all.

Here is my configuration:

S3:

CloudFront:

Lambda@Edge (executed at Viewer request)

exports.handler = async (event, context, callback) => {
    let request;
    let token;

    try {
        request = event.Records[0].cf.request;
        const headers = request.headers;
        const authorization = headers['authorization'][0];
        const authorizationValue = authorization.value;
        token = authorizationValue.substring(7);
    } catch (error) {
        console.error("Missing authorization header", error);
        callback(null, missingAuthorizationHeaderResponse);
    }

    if (token) {
        try {
            if (!secret) {
                secret = await getSecret();
            }
            jwt.verify(token, secret);
            console.log("Token valid");
            callback(null, request);
        } catch (error) {
            console.error("Token not valid", error);
            callback(null, invalidTokenResponse);
        }
    } else {
        console.error("Token not found");
        callback(null, missingAuthorizationHeaderResponse);
    }
};

I will be very grateful for help since I've spent a lot of time on this case, thanks!