Date since last added in Power Query or DAX

mshilendhari - see if this is what you want. If not, please provide data per links below and how the calculation should be arrived at. The below M code turns this:

into this. You can see the items in red retain the latest Watchlist date for the same item.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUbLUN9Q3MjAyADLDE0uSM3Iyi0uUYnVgkkb4JI1hkp55xQWpySWZ+XlIsibYtToBRSxwWQqRxGEpRNIYn6QJDhdBZE2xycYCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Item = _t, Date = _t, Status = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}}),
    #"Grouped Rows" = 
        Table.Group(
            #"Changed Type", 
            {"Item"}, 
            {
                {
                    "WatchListDate",
                    each
                        let
                            varStatus = "Watchlist",
                            varGroupTable = _
                        in
                    
                    Table.AddColumn(
                        _,
                        "Test",
                        each
                            let
                                varCurrentDate = [Date]
                            in
                            List.Max(
                                Table.SelectRows(
                                    varGroupTable,
                                    each [Status] = varStatus and [Date] <= varCurrentDate
                                )[Date]
                            )
                    )
                    
                }
            }
        ),
    #"Expanded WatchListDate" = Table.ExpandTableColumn(#"Grouped Rows", "WatchListDate", {"Date", "Status", "Test"}, {"Date", "Status", "Test"})
in
    #"Expanded WatchListDate"

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How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.