String substraction from another string

Hi ValeriaBreve, you made a mistake probably, so I've edited your sample data a bit

Result

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("HYq7CoAwFEP/5c75hQ4q6Kioi5QOggELpZWKj8/32iUh58RaqQRSHUegGbjmU1dpjKs/fURR4mClVjVy01wYQnrQZTLiR79uVEy8GU3rb5rJvwr6SMxPwrzrF226MspHnPsA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Main = _t, Category = _t, #"Category 2" = _t]),
    Ad_Final = Table.AddColumn(Source, "Final", each 
        [ a = Text.Split([Category], "="),
          b = Splitter.SplitTextByAnyDelimiter(a)([Category 2]),
          c = Text.Combine(List.Select(List.Transform(b, (x)=> Text.Trim(x, {" ", ","})), (y)=> not List.Contains({"", null},y)))
        ][c], type text)
in
    Ad_Final