I have no insight into @manton’s implementation, so I can’t say for sure, but according to the documentation all images should automagically work within 48 hours after the domain change:
When adding a custom domain for the first time, or changing to a new one, various things may appear broken for a while:
None of your images will load
HTTPS won’t initially be enabled, so visiting your site may show an “insecure message”
Both of these are normal. Behind the scenes, we’re automatically setting everything up. Things should clear up in about 48 hours.
When I changed domain names, the photos in my blog became visible on the new domain. There was an issue at first, but it had to do with it being a complete domain name change, not just an additional domain.
First, I recommend doing a backup (Posts → “…” → Export) in the Blog Archive format. I’ve improved it recently and having a fresh copy with all your photos will make sure you have everything if something goes wrong.
As for the rename itself, if you are just changing the domain name and not deleting the blog in Micro.blog, then all your uploads should be preserved. It should also update the links automatically, but if it doesn’t, drop an email to help@micro.blog and I can make sure it’s updated.
So now I am confused. 24 hours after making the change with domain names and my images are appearing in the blog itself, but if I go to the Uploads section of my account all of the uploads there just show as “?” with their URLs set to the old domain name.