I've run into exactly this issue at a past job, multiple webapps run by different teams that were "tabs", with a central auth system. I turned up, saw this and couldn't believe my eyes. Basically because teams couldn't agree on working together, they made this horrid attempt of a service based architecture and the result was chaos. I know monoliths are not popular, but they have their place in early stage companies where moving fast v's having a trendy design is critical. Company went out of business a few years later...