The OTB Provider QGis plugin is now available on QGis plugin catalog. Since QGis version 3.36, the plugin previously packaged is no longer in QGis package.
To use OTB with QGis 3.36 you need to install plugin from QGis plugin catalog (“Extensions menu –> Install/Manage Extensions” and type OTB in not-installed tab). Then follow plugin settings instructions available on Cookbook.