How to Capture User Behavior and Convert That User Behavior Into Tests

The way I see it, we indeed switched from yearly releases or quadri-releases to weekly daily. And that's mostly, from my perspective, because of testing. Testing was really problematic. Doesn't matter how fast you write the new three lines of code, you need to do regression testing that takes months,. Now we don't do that anymore, right? But now I feel that we have a different problem is, and that problem is, okay, this does not work. How didn't we caught up, caught that? Hey, nobody talked about that scenario, right? Nobody talked about this scenario, nobody talk about that scenario. That's happening in production for months now,