So, this simple server migration that was only supposed to take a couple of hours? Took a lot longer than that.
As usual, in the end it was just that one setting that everybody forgot to change that was the problem. Some older posts might perhaps no longer display their images due to some changes in database configuration – the pics can be recovered if you let me know about the problem for any particular post.
The new look needs a little tweaking before it runs perfectly too. That will happen in the background.