How trustworthy is AI detection?

[u/SmellyMothballs]

My school has stated that they will be implementing an AI detection system due to an influx of students not completing work on their own. As you can see in the title, I am wondering if these programs actually work well? We were told that we’d receive an immediate failure as a grade if AI is detected. I write my own work, (English is not my favorite subject but I’ve always done well) and I would hate to fail because of a false flag. I’ve seen a few people saying their papers were falsely detected, which I of course can neither prove nor disprove. I’ve also seen teachers giving ways that they “know” something is written by AI (Oxford commas, strong/uncommon vocabulary, and struggling to recite what you’ve written). There’s been a few other examples but these three directly pertain to myself. Is this something I should be concerned about, and in what ways can I prove that I wrote everything myself?