I highly recommend you install the Copyleaks/Origin browser extension and just scan your post before posting if you doubt that the third-party grammar assistant might have changed your post too much. I consider it my responsibility, too, as when you are fighting against the unethical use of AI, you must scrutinize yourself in the first place. It is the same as submitting your research paper/article to any reputable platform as your own, you are required to scan it for plagiarism/AI detection before final submission.
As I said in my previous post, I am not going to use Grammarly AI anymore because that destroys my own writing style. So, I don't think I have to check my own post before I submit that. Moreover, I do not actively look for AI-generated contents that other users may post. I just do my regular things, and if I ever suspect any posts that might be written in AI, I only then check their posts and then report them.
Thank you for your suggestions anyway. I love to ask people what they should I do because I believe the community is a strength. If I do something wrong, it is better to find my own mistake by myself.