I received a mail from RT pointing tohttps://about.readthedocs.com/blog/2024/07/addons-by-default/ and explaining that ptb currenlty relies onhtml_baseurl and that it should be set via

importos# Set canonical URL from the Read the Docs Domainhtml_baseurl=os.environ.get("READTHEDOCS_CANONICAL_URL","")# Tell Jinja2 templates the build is running on Read the Docsifos.environ.get("READTHEDOCS","")=="True":html_context["READTHEDOCS"]=True

This is also explained somewhat in thecurrent docs

Additional changes may be needed to adapt toRTD addons - in particular they include a nativesearch as you type addon. I'll create a spearate issue for that and link to the furo theme issue tracking the topic.