The Switch Page Theme module does nothing to help. Among the Opigino module files, I couldn't find references to ThemeNegotiatorInterface. I found a modules with multiple references to the parent theme in the *.yml install file.
status: true dependencies: module: - group - opigno_learning_path theme: - platon id: opignogroupoperationsblock theme: platon
Does that mean it's set in the database for these pages and this module? Is it possible to create installation yml files that override these?