Over nearly 10 years in startups (big and small), I've been consistently surprised by how much I hear that "testing has been solved", yet I see very little automation in place and PMs/QAs/devs and sometimes CEOs and VPs doing lots of manual QA. And not only on new features (which is a good thing), also on happy path / core features (arguably a waste of time to test things over and over again).
More than once I worked for a company that was against having a manual QA team, out of principle and more or less valid reasons (we use a typed language so less bug, engineers are empowered, etc etc), but ended up hiring external consultants to handle QA after a big quality incident.
The amount of mismatch between theory and practice in this field is impressive.