Hi liubin,
经过我的测试，我重现了你的问题，你可以尝试下面的代码来启动浏览器来打开相对应得网址。
ProcessStartInfo psi = new ProcessStartInfo
{
FileName = "https://www.baidu.com/",
UseShellExecute = true
};
Process.Start(psi);
根据搜索，我找到了原因，当我们使用.NET Framework程序时，UseShellExecute默认为true，而.Net core程序默认显示为false.
你可以看看下面的链接去了解更深入的原因。
属性值
How to start the system default browser
希望可以帮到你。
Best Regards,
Jack
MSDN Community Support
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