Earlier quoted context omitted.
As a developer I've had some very good and very bad experiences... usually centered around two issues.. 1. I am not a morning person and am consistently late, I get work done, but not at 8/9am on the dot. And, 2. because I will take the time to understand what I am working on... this usually results in some refactoring and generally less code in the end. I once saved enough code in size to include lodash, and eventem…
From the outside, it's rather hard to tell the difference between someone getting problems that are "inherently simple" and someone spending time finding simpler solutions to problems.
Even within "just a web app" one can run into some gnarly issues or odd old code that renders otherwise simple tasks difficult, but since it's only one person working on it you can't really test whether or not it's actually difficult.
This might impact both the dev/manager disconnect as well as imposter syndrome.