Not seriously anyway. It’s fine if you’re joke-apologizing for writing angst or a cliffhanger or whatever, but saying things like “I’m sorry this is shit” or “this chapter’s really boring, I don’t know why I wrote it”, helps no one, especially not you.
You are a strong, confident author who’s written an awesome fic! You have nothing to apologize for!
That’s the you to be presented when you’re posting on ao3. All the worry and self-doubt belongs in private conversations with your friends. Not in your author’s notes at the top of the page.
Putting apologies at the start of a fic or a fic chapter (or, god forbid, half way through) achieves nothing. It won’t make readers sympathetic to your plight. The nice ones will just, consciously or unconsciously, start looking for these failings or errors you’ve mentioned, which they probably wouldn’t have even noticed before. The nasty ones will sense weakness and attack in the comments.
If you need someone to hold your hand and tell you you’re doing ok, that’s fine. Lets face it, we all need that from time to time, especially when we’re putting ourselves out there and posting our fic, making ourselves vulnerable. But your readers aren’t the ones to do it for you. And making yourself more even vulnerable by letting them see your insecurity is not good for you and not good for your fic.