SOLVED:My template at "/conf/<root>/settings/wcm/templates/page-basic/initial" was missing the fragmentVariationPath property on the experience fragments. I'm not sure why it still worked on the author instance, though. Thanks for your suggestions.

That didn't seem to have an effect.

Root configuration is the same on both instances.

The value I have there is like /conf/<root>/settings/wcm/templates/page-(.*)

How do I check that? CRX only shows /content on the publish instance.

Going directly to the header/footer experience fragment works.

I'm using editable templates with the header and footer as experience fragments. On author this works as expected, but on publish the header and footer are missing. In the publish log, I see this:19.05.2022 17:01:30.302 *INFO* [127.0.0.1 [1652994090260] GET /home HTTP/1.1] com.day.cq.wcm.foundation....

Also, please don't assume that your reply is the answer. If you can change the correct answer for this post, please do. 

It doesn't need to be escaped. I found another error further up in the log and resolved it. This was just some weird side effect. 

I'm using AEM 6.5. I tried escaping with a backslash, but got the same result.