The reason is very clearly: posts+sig ad, It's clearly that you had made some useless posts on the forum, because your posts seems random with no punctuation and language structure.
If you want to learn more, please read more "banned" related threads on the meta section.
i remember clearly, my last most posting in bitcoin discussion and marketplace boards
i do not post on random boards, but after i check my last post the topic was moved into other boards
You are not banned without reason. You can see from the screenshot you just provided that you have insubstantial posts + sig ad.
You are wearing the bit-x campaign paid signature and most of your posts are 1-3 lines without any real meaning.
Just be careful do not create an alt account and go post somewhere other than Meta. That'll get you a permanent ban for ban evasion.
it is true that i join bit-x signature campaign
yeah, my post about 2-3 lines and some of them more than 3, and it's still on topic, when someone ask i'll try to help
and my post is not spamming
thanks for your warning
It's doesn't matter where you post, 1-lines-posts will be OK too, all is about the quality of your posts, constructive? useful?
Some users are making more than 30 posts a day, but they are fine so far, because they make constructive posts.