A 2018 review of what we learned about American suburbs ends with this:

It all added up to a portrait of suburbia as a landscape of dynamic cultural and structural change, not sleepy stasis.

I would suggest this is a change that has been happening for decades. Here are the first four features of a more complex suburbia that come to mind. They each go back quite a while:

1. Different kinds of suburban communities. The prototypical suburban community looks like Riverside, Illinois or Levittown, New York, places primarily for commuters, consisting of single-family homes., and attracting middle to upper-class residents. These communities had a limited numbers of jobs and local businesses and men were expected to commute to the big city (via train or automobile). The problem with this view, common to find since any book on the history of the suburbs mentions these two bedroom suburbs, is that different kinds of suburbs have been around for at least a century. Different kinds of suburbs included: working-class suburbs, suburbs of non-white residents, industrial suburbs, and suburbs with various levels of density of housing and commercial or industrial property (including edge cities).
2. The move of industry and jobs to the suburbs. Even as a good number of early suburbs were bedroom suburbs, the suburbs also proved attractive to industry because of cheap land, access to transportation, and the ability to pollute away from millions of residents in the big city. East St. Louis, Illinois or Gary, Indiana grew as industrial suburbs. After World War Two, the number of jobs grew in suburbs as businesses moved to the suburbs to be closer to workers (or perhaps closer to their CEOs) and suburban residents desired more goods and shopping options (shopping malls, big box stores, restaurants, etc.). By more recent years, the most common commute in the United States was suburb to suburb, not the supposedly typical suburb to big city commute.
3. Changing suburban populations. While most early suburbs were white (notwithstanding the occasional community of non-white suburbanites who could not live in white suburbs), suburbs in recent decades have become home to an increasing number of non-white residents. Additionally, poorer residents have made their way to the suburbs in recent decades. These non-white and poorer populations may have hit a certain critical mass in recent years but the trends go back at least a few decades.
4. Growing cultural and entertainment options in the suburbs. This trend is more recent than the first three but is still relatively common across metropolitan areas: suburbanites do not need to go into the big city for entertainment and cultural options. The suburbs feature a number of restaurants, museums, parks, music venues, festivals, and other options that make it easier for suburbanites to rarely need to go into the big city for a night out. Certain cultural options may still be richer in the big cities but more regular cultural options are now often found just a few suburbs over.

All of these suburban features may be coming together in new ways or presenting challenges to more suburbs that never thought they would change dramatically from their character at founding. Additionally, thinking about these intertwined suburban traits could help us move past seeing cities and suburbs in a strict dichotomy and instead view metropolitan regions as more cohesive wholes with similar interests and problems to address.