My perspective based on the places I've worked:

* Jr Engineer - Your work is given to you as bite-sized well-defined tasks.

* Mid-level - You're working on and delivering entire projects. The project is often well-defined.

* Sr Level - You're more working on a problem space, and it's much more open-ended. You may have to come up with and define your own projects.

* Tech Lead - Your focus shifts from your own impact, to the impact of your entire team. This is the biggest shift, where you need to spend way more time communicating, getting alignment with multiple teams, etc.

I sympathize with OP for missing the days of only working on well-defined tasks. However, being able to tackle open-ended problems is a huge value to businesses and it's the reason senior engineers make a lot more.