after searching through the forums, there was already an explanation why this has not yet been implemented. just gonna plug it here for future people: https://forums.mangadex.org/threads/option-to-exclude-mangas-from-my-library-in-advanced-search-rejected-technical-reasons-dev-reply.1076334/...
As someone who reads manga whenever something is interesting in the title, cover image, and/or description and put its status in "Reading", the amount of Manga that has a "Reading" status in my Library has amounted to thousands and my MD Lists still accumulates as new manga keeps releasing. I...