I can relate. One of the very first realizations I had about writing is that if you want to write a brilliant character, you might have to be even smarter than you want that character to be.
At the time I was reading Gordon Dickson's "Tactics of Mistake", which was about a brilliant young military officer. I wondered if I could ever match such plotting.
A few years later when I read it again I wasn't as impressed.
If I leave a WIP for a while and go back to read it to "catch up" and get back in that frame of mind, sometimes I really like it and wonder if I can re-capture whatever I was doing to write what I really liked. It's tough to wonder if you can be as good as you! LOL
That happened to me just this afternoon. I pulled out something I wrote two chapters of some time back to stick the first three sentences in that thread. I wound up reading both chapters and kicking myself that I haven't written more of it yet. I liked it. I don't consider it bragging, for if we don't like what we write then what the heck are we doing?
Go back and read something you wrote and haven't read for a while. Do you like it as much as authors you've recently tried out? You very well might.
If you don't, think about what they did and compare. Any time we stop learning and stop improving, we're done.