In rare cases, it might be a fragment of a larger sentence or a mistranslation from the Romanian site where the file originated (e.g., a "piece" of a collection or "piesa," which can mean "piece" or "part" in Romanian).
Because One Piece and Bleach are both members of the "Big Three" shonen anime, sometimes users or automated tools mistakenly associate the word "Piece" with other long-running series files. [Anime Kage] Bleach - 358 [BD 1080p RoSub].mp4
In the context of that specific file name, is not a standard technical tag. Instead, it is highly likely a misinterpretation or typo related to one of the following: In rare cases, it might be a fragment