Recent notable example is Crimson Desert, they spent years building their own engine for this game and IMO they raised the bar when it comes to creating a huge realistic world.
Others that come to my mind are Decima and RE Engine.
While the company is extremely proud of its proprietary engine, I was told it causes severe internal politics. The studio is heavily biased toward the engineers who built the engine. Another huge downside is the lack of documentation—you can't just Google your bugs. (Granted, this was the situation two years ago).
The CEO is famously known in Korea for prioritizing developers while devaluing writers and planners. However, even within that developer-first environment, the proprietary engine has birthed a clear internal hierarchy among the programmers
id Software, the new Doom series uses highly performant engine (as if there was some legacy there for that).