Yes, the “alternative logo” component we were using for the dark themes isn’t compatible with the latest improvements to core. I’ve added a temporary fix to meta, made some extensibility improvements to core and made a pull request to the component so that it should be more future-proof.
https://github.com/hnb-ku/discourse-alt-logo/pull/1
@danekhollas try refreshing your browser, it should be ok now 