The litmus I use to determine if I've been promoted to incompetence is whether my presence improves situations or not. There have been cases where I joined projects and didn't improve things or — unfortunately — made things worse.
All you can do is address the problem openly, find strategies to improve the situation, and try to find ways to remedy it.
If you can't, well, you've got to regress a bit and restore a role you're competent in. I think a common strategy is to try and shift blame or manipulate situations so it isn't obviously your incompetence that caused the problem. Many people might even do this without realizing it. I certainly did earlier in my career, but I never intended to lie or trick people. It was mostly the conflation of insecurities and imposter syndrome, along with my inability to ascertain my actual skill level. In self-defence I'd try to protect myself from the reality that I was doing a bad job.
The only way to get promoted without eventually reaching incompetence is to rinse and repeat that process, as far as I can tell.
I was once in a position that I was sure was above my competency. It was certainly above anything I had ever done before in terms of responsibility. It ended up working out well, I think because I knew I didn't know what I was doing so I asked for a lot of input from others and tried to do what seemed the most sensible after considering that.
The funny thing is, it was for a volunteer organization, not a paid job. I would not do it again, because (for me at least) it ended up being way more work than I thought it would be. But it was a valuable experience.
I find it hard yet possible because I know I’m unable to function well when I’m not outputting my best work. It weighs on me. My goal is to be the best part of a team I can be, because the goals of the team (rather than my personal goals) matter to me (otherwise I wouldn’t be on the team).
It’s a little dumb but also a good sustainability mechanism for my career more generally. If I was promoted to incompetence I think I’d have a bit of a crisis of imposter syndrome, purpose, and meaning, and wind up needing an expensive break or something. My employment references would be worse, my network lower quality. I’m loosely hypothesizing here, but that’s the general idea. I want to be able to go to work and feel like I’m doing the right stuff, and doing it well. If it takes longer to advance, that’s fine with me.
All you can do is address the problem openly, find strategies to improve the situation, and try to find ways to remedy it.
If you can't, well, you've got to regress a bit and restore a role you're competent in. I think a common strategy is to try and shift blame or manipulate situations so it isn't obviously your incompetence that caused the problem. Many people might even do this without realizing it. I certainly did earlier in my career, but I never intended to lie or trick people. It was mostly the conflation of insecurities and imposter syndrome, along with my inability to ascertain my actual skill level. In self-defence I'd try to protect myself from the reality that I was doing a bad job.
The only way to get promoted without eventually reaching incompetence is to rinse and repeat that process, as far as I can tell.