Voyager incompatable with Lemmy 18.5 installed from scratch

**Describe the bug**
As of 2025-08-23 Lemmy Version 18.5, installing the lemmy backend scratch (using the official instructions [here](https://join-lemmy.org/docs/administration/from_scratch.html) produces an error (`Problem connecting to {server url}. Please try again`).

This is using both the ios app (version 2.39.2) and Voyager 2.39.3 Beta Track – [752] 7982ff0 at [[https://beta.vger.app/]]

The lemmy instance is otherwise functional. (and nonfederated)