要删除查询字符串，可以尝试Middleware，如

app.Use(async (context,next) =>
{                
    if (context.Request.Query.TryGetValue("fbclid", out StringValues query))
    {
        var items = context.Request.Query.SelectMany(x => x.Value, (col, value) => new KeyValuePair<string, string>(col.Key, value)).ToList();
        // At this point you can remove items if you want
        items.RemoveAll(x => x.Key == "fbclid"); // Remove all values for key
        var qb = new QueryBuilder(items);
        context.Request.QueryString = qb.ToQueryString();
    }
    await next.Invoke();
});