It never fails. No matter how many people see your book before it is published, once it is released, you’ll get comments from people saying that it needed to be better edited.
If the people making the comments can list specific issues, take a look at them and make changes if necessary. I usually don’t worry unless multiple people talk about a book’s editing.
I also do read-throughs of my books every four or five years just in the process of updating things such as a new cover, updating the ebook, or something else that has brought the book back to my attention.
As an independent author, you need to learn to be a better self-editor. I say better because it is something that you never stop learning to do. You can always be better.
I know I’m always looking at how to better edit myself. I’m reading Self-Editing for Fiction Writers by Renni Browne and Dave King. It’s not revealing any surprises to me, but it is reinforcing things that I know. My hope is that the more I reinforce how to self-edit and do it, the more it will become part of writing habits.
Just because I self-edit doesn’t mean that I won’t have other readers and editors review the manuscript, it just means that (hopefully) I will be sending them a cleaner, more polished book.
To get you started on your self-editing journey, here’s a link to an article that will give you some tips.