What happens as you accrue years of experience is, you feel as if you learned a lot, actually its yes and no, yes because working in an environment with deadlines teaches things, no because the tech is changing.

The fact is tech is changing every few months if not year, one should be having a baby's curiosity to learn and adapt to the new practices.

When I started my tech career I was having a growth mindset, as I went on I felt somehow I got into a fixed mindset and got frustrated often. It's better late than never to realize that you may get wrong more often than right and learn to have an open mind when working.

Finally always take it easy on yourself, learn and move on.

Which backend language has the least learning curve and you can scale your knowledge and learn cool things further down the lane ?
For me it's Python.