I remembered I saw my site’s SSL was not working. So I visit it today (how lazy I am). I see it’s complaining my cert belongs to blog.diamondtin.com instead of www.diamondtin.com. I forgot why I choose www.diamondtin.com over diamondtin.com, but I’m sure I have long abandon the domain blog.diamondtin.com.
SSH to my server I found my certbot settings is very messy. That auto detected config changed my nginx config and somehow prioritize the blog.diamondtin.com as the primary domain name. So I manually deleted the domain from certbot and nginx. Restart, and it seems OK now. If you still experience problem, please ping me on twitter @diamondtin.