One may amend that most mature industries tend to move to an apparent stagnant state as the Capex for r&d increases over time, sometimes due to regulation and/ or due to increased technical complexity. There is also a point at which you can't optimize certain aspects further and have to figure out where to pivot innovation, e.g. end of dennard scaling/Moores law.

Most of them are stagnant. That's why breaking up incumbents under antitrust laws is a great idea. GenAI and some sectors of the entertainment industry are pretty robust, but otherwise it's not great out there broadly speaking.