Nothing personal
Outside of grammatical errors, one of the biggest culprits of (negative) feedback from clients for writers is simply a lack of understanding about the subtleties of the topic or who you’re writing for.
That if you start from the wrong assumptions, you shouldn’t be surprised when you get it wrong. Because you will.
Part of being a professional is doing your research—taking the initiative to ask the right questions to avoid making the wrong assumptions at the start.
The second half is acknowledging that errors and misjudgments are bound to happen, no matter how much you prepare.
That while you can blame the client, or your boss, or a mediator, for not being clear at the start, it’s simply more effective (and productive) to acknowledge what’s wrong and fix it.
No judgement, no problems.