As others have suggested, if you are terribly worried about spelling and grammar then you should use something like Grammarly. Nobody would mind that.
Grammarly is slowly morphing into a full-blown AI writing assistant. If I look at their home page, I see taglines like: "Responsible AI that ensures your writing and reputation shine" and "Work with an AI writing partner that helps you find the words you need—to write that tricky email, to get your point across, to keep your work moving."
They're making a company-wide push to be involved in more than just the "revision" stage of writing:
To date, we’ve been focused on the revision stage of the communication lifecycle. By embracing new technologies like generative AI, we can advance our vision of supporting the entire process—from conception to comprehension. Grammarly is committed to using the most effective technologies available to solve real individual and organizational problems in everyday communications—from overcoming writer’s block to tackling an email backlog in minutes, and more.
Personally, I wouldn't use Grammarly; at some point, there's going to be little to no (plagiarism-wise) difference between using it or something like ChatGPT to improve your writing. (For the record, I don't have a problem with generative AI being used to improve and paraphrase writing, what I have a problem with is using it, for anything,
without credit: I can't see how an attribution requirement would upset anyone but those wanting to
appear to possess a skill that they're actually missing.)
Also, even before embracing generative AI (so, a little unrelated to this discussion, but, still worth pointing out, I think), Grammarly has (as far as I know) always been a closed-source online-only profit-driven black box... Definitely not the smartest thing (privacy-wise) you could choose to become reliant on and habitually pipe most/all of your writing/correspondence through.