I check all my deleted post. I’m sure that it's not a spam because it's same quality on all of my post. I notice that this an attack because all the reported post was made a month ago and its in consecutive order.
Moderators carefully review your post before they delete it, so you can't be absolutely sure it's not spam even if you didn't mean to send it. The problem might be that some people are interested in reporting a user's old post or two, but so far that's not what I'm reporting. I tend to report the latest post that I accidentally come across in several different thread, this saves me a lot more time than accidentally reviewing posts from one profile to another.
About spam or not, it depend on the moderator who handle the report because I'm sure they will review the report one by one before marking our report as good, bad or not handled.
Question: At what certain amount of deleted post will cause a permaban? I lost count because I delete all this notification on my message because it's already annoying at that time.
Only moderators know the amount. But when you keep getting posts deleted within 24 hours up to 30 - 50 posts, then it's very possible moderator ban your account with temporary ban.