Conversation.js doesn’t really support changing domain names. When you visit that old post, this URL will fail to load:
https://micro.blog/conversation.js?url=https%3a%2f%2fmattlangford.com%2f2023%2f01%2f14%2fwere-staying-in.html
That’s because there newer was a blog post with that path on the Micro.blog timeline. The original post was published to mattlangford.micro.blog. Conversation.js isn’t smart enough to figure that out.
Also, see my and Manton’s replies in this thread.
One way to work around this limitation is to do a check in the template. Is this an old post? Then fetch conversation.js with the old domain name. If not, use the new domain name.