csc static template "v4.3" won't include the registered plugins
If you upgrade from 4.3 and choose the css_styled_content static template "v4.3/", no frontend plugin from extensions will be rendered in the frontend.
Switching to another css_styled_content template will make the rendering appear.
FE-plugins are registered through
which include typoscript code right after the "content (default)" or "css_styled_content". This is currently hardcoded in t3lib_extmgm::addTypoScript.
When we added the v4.3 static template, we forgot to update the array or content rendering templates.
Solution is to move the hardcoded array away from the core and provide a registry of renderingTemplates which css_styled_content then uses (including the new v4.3 template).
(issue imported from #M14231)