If value is TRUE, replace value from another table where one column equals another column

Hi NMorenoLAC,

amustafa created solution in DAX so I created one in Power Query.
Important: I'm not sure if you have null values as power query null or as text "null". I've used text "null" in my query. If you have default PQ null - let me know and I'll update the query.

How to use my query:

1st: create blank query, open Advanced Editor, delete whole code and paste there my query.

Then:

Query:

//If value is TRUE, replace value from another table where one column equals another column
//https://community.fabric.microsoft.com/t5/Power-Query/If-value-is-TRUE-replace-value-from-another-table-where-one/m-p/3671868#M120793

let
    Table_TagNames = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WCklNzFUwVNJRCk9NKs4sSS0GMvNKc3IQVFBqQX5RCbp4rA5UrxFCIjg1ubQos6QSxCwtAOlCyLkkFmck5ScWpRRjmGAMFHEsKMjJTE4syczPQ7LJPb8stSgvMS85FcNVHqk5BSmpxdlKsbEA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [team = _t, blue = _t, aqua = _t, darkGreen = _t, pink = _t, lime = _t, red = _t]),
    Table_TagNames_HeadersLower = Table.TransformColumnNames(Table_TagNames, Text.Lower),
    Table_PlannerTasks = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WCkkszvZ0MVTSUQpJTcxVADOCQl2BVF5pTg6CwiIYqwPTbgTTboRXA6ogQrsxTLsxMdZCBRHaTXBrx0qhaTfF4nh8tqM53gw56HDbh6Y9FgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [taskId = _t, team = _t, tagblue = _t, tagAqua = _t, tagDarkGreen = _t, tagPink = _t, tagLime = _t, tagRed = _t]),
    Source = Table_PlannerTasks,
    Table_PlannerTasksHeadersEdited = Table.TransformColumnNames(Source, each if Text.StartsWith(_, "tag") then Text.AfterDelimiter(Text.Lower(_), "tag") else _),
    MergedQueryItself = Table.NestedJoin(Table_PlannerTasksHeadersEdited, {"team"}, Table_TagNames_HeadersLower, {"team"}, "Table_TagNames_HeadersLower", JoinKind.LeftOuter),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(MergedQueryItself, {"taskId", "team", "Table_TagNames_HeadersLower"}, "Attribute", "Value"),
    Ad_Color = Table.AddColumn(#"Unpivoted Other Columns", "Color Tag Name", each Record.FieldOrDefault(Table.ToRecords([Table_TagNames_HeadersLower]){0}, [Attribute], null), type text),
    ReplaceValues_ValueColumn = Table.ReplaceValue(Ad_Color,
     each [Value],
     each [Color Tag Name],
     (x,y,z)=> if x = "TRUE" then z else y,
     {"Value"}
),
    #"Removed Columns" = Table.RemoveColumns(ReplaceValues_ValueColumn,{"Table_TagNames_HeadersLower", "Color Tag Name"}),
    #"Pivoted Column" = Table.Pivot(#"Removed Columns", List.Distinct(#"Removed Columns"[Attribute]), "Attribute", "Value"),
    RenamedColumnsBackToOriginal = Table.RenameColumns(#"Pivoted Column", List.Zip({Table.ColumnNames(#"Pivoted Column"), Table.ColumnNames(Source)})),
    Ad_allTags = Table.AddColumn(RenamedColumnsBackToOriginal, "allTags", each Text.Combine(List.Select(Record.ToList(Record.SelectFields(_, List.Select(Record.FieldNames(_), each Text.StartsWith(_, "tag")))), each _ <> "null"), ", "), type text)
in
    Ad_allTags