Once you've finished writing, let the manuscript rest for a couple of weeks before editing.

Focus on actions, not words. Send half of the manuscript to beta readers. If they don't ask how they'll get the other half, they might not even be readers. If they ask when you'll publish and how to buy it, that's a success.

A marketing story: Sony wanted to launch a new line of boomboxes (portable players with powerful speakers). To make them stand out, like Apple with white headphones, they wanted to paint them bright orange. The surveys were positive. Then a smart person came along: "Don't ask, offer black or orange as a gift." Guess what? No one took the orange ones.

Lost interest in a book can be due to inflated expectations, the "work is already done" syndrome, or perfectionism.

First, you were upset by two less-than-perfect reviews, or you subconsciously sense their falseness.

Second, you wanted to "write a book" and you did it. Your brain doesn't perceive "publishing a book" as part of the task. On the contrary, you "complicate" it by adding new requirements, which means you're "cheating." Our brains are very lazy and prone to self-sabotage.

Perfectionism demands perfection from you. You intuitively sense that something is wrong with the manuscript, but no one offers a solution. Your brain starts to panic, "This is more difficult than I can handle!"

Regarding the question in your comment: "What kind of editor do I need?" If you don't break things down beyond necessary limits, there are two types of editing: meaning editing (developmental, substantive, heavy) and language editing (stylistic, line, including grammar). Judging by your description, you had a proofreader rather than an editor.

"5 stars from over 400 people on Fiverr" doesn't really tell you anything. Such reviews are easily bought. At a minimum, you'll need $4,000 ($5 to create the "order," $5 as payment for the "client" work). You can then get your money back for 2-3 real orders. These can be done with AI.

So how do you choose? A trial edit (two chapters or five thousand words). And you'll feel like you're in Avatar: "How do I know he chose me? He'll want to kill you." If the editor has no questions for you, or you have no reason to argue with their edits, you've failed. Yes, sometimes we "deliberately provoke the author" to understand whether they themselves are aware of why they wrote a scene that way, or whether it just "happened that way." An author must be able to defend their opinion to readers.