Sometimes coworkers does not like that because they don't see me working on the problem, but on a tool which will resolve the problem and similar problems from our backlog.
I wouldn’t overthink this.
Even in a big corp there are always problems to solve. The point is to find problems that both:
1) are hard enough that someone junior won't be able to solve them alone, and
2) actually provide value to the company / users
I managed to get a couple of smaller tools out recently thanks to having copilot available to churn on them while I spend my time on prescribed work, but it would consume all of my time to even make a significant dent in it.