[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:

The file tag "[BD 1080p RoSub]" already covers the technical details: BD: Blu-ray source. 1080p: Full HD resolution. [Anime Kage] Bleach - 358 [BD 1080p RoSub].mp4

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. In the context of that specific file name,