Why is my additional information to a wikipedia article removed behind my back ?
You should tell what change to what article it was if you want a clear answer. There could be various reasons. Your addition could be considered opinion rather than fact, or it could be considered irrelevant to the subject of the page, or it could be unsourced and disbelieved, or it could duplicate information elsewhere on the article, or they may have mis-recognized you for someone who habitually includes false information, or someone checking for vandalism had done so too long and misidentified your addition as such, or…