After I did an upgrade to latest magento CE version 22.214.171.124, I noticed 2 weird changes:
frontend: home page url was changed to /STORECODE/cms/index/index
backend: once an admin user logged in, he will face 404 error, the url is admin/index/noRoute
I've no conflicts. All modules have been updated to the new routing. Other admin functions are working and frontend pages are working as expected too.