Based on search patterns and industry slang, "Collection M" most likely refers to , with the "M" potentially standing for "mature," "movies," or "mega-collection." It is frequently used by third-party websites that curate and index bold content from various OTT platforms. Understanding this distinction is crucial: you will not find a series officially named "Collection M" on the Ullu app itself, but you will find many of its unrated originals that such compilations might pull together.
Always watch on the official Ullu app. Pirated versions of "Collection M" often contain malware or horrific video quality. Collection M -- Ullu Unrated Web Series