ECS architectures are used in a number of young open source game engines, such as Bevy[1]. I haven't done game development for a long time, but hearing about an architecture that does away with the heavy and complex OOP you often see in games makes me want to dip my toes in again and check it out.
There's also a history in applying ECS in older things, it started taking off in early 2000's, it's been bread and butter (though not universal) for long now, also in some open source engines. See eg https://github.com/Adelost/entity-component-systems-study#re...
[1]: https://bevyengine.org/