I was watching this while it was happening.
A user was targeting your comments, which contained "Thanks", with a "no longer needed" comment flag. Flagging such comments can sometimes unilaterally delete them just with 1 flag. This appeared to be the case. I undeleted your comment, since I thought that comment could surely stick around, but the user flagged it as no longer needed again. You then reposted your comment a couple times, and the user instantly deleted it again and again (this happened 4 times).
You then posted this comment, which was also somehow able to be instantly deleted with a single flag (in this case it was "unfriendly or unkind"). The use of such a flag didn't make any sense to me, so I undeleted it, and was going to tell the flagger to knock it off when, seeing that it was back, they flagged it again (this time with "no longer needed") and it deleted it again.
In the case of that last comment, another mod on the network informed me that it looks like there's a filter that's still catching onto a word or two. I'm not sure how well-known the keyword that's triggering the script is so I'm not going to disclose the exact word(s), but I feel a bit better knowing that it's at least somewhat intended functionality.
I've instructed the flagger not to do this again. Sorry for the confusion.