Need help with this power query

There should be more elegant solution, but until somebody provides it, you can try this

 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("7dZNi8IwEAbgvzL0LNrETbWeRE+FPVlvIou2s92CSaRJhf33O0pd6kcxBxHRFgplIA/TMnmbxcLjTAxCn3sdj4keYz3ucwZi1GdUmaOxpcFibOmhm2hJtQlmuQLzqxIocJebXCuqwuFedo5e39mb/qxUhvCZK4TIomyxZ8LAmZlVwwAxjQamlbJfRZf48lmtucBZjetzBlTbbtD+6/UXHl6YYYMZya0u7BUidCfoO0Gkkk2ZYgq0H+JybfAO5gyl3hH5XWjZoi3aog9BxVkicT76aFKbf4BV2AUnYScG7vTtXH8xrSmKxfCujb2PFj6lBu7O9WNEranAd8dunh6Wfw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ID = _t, #"Date/Time (UTC)" = _t, User = _t, Description = _t, #"Security Change" = _t, #"Previous Value" = _t]),
    Custom1 = List.Transform(Source[Description], each if Text.Contains(_, "sync revision", Comparer.OrdinalIgnoreCase) then "x" else null),
    Custom2 = List.Transform ( List.Split( List.PositionOf( Custom1, "x", Occurrence.All), 2), each List.Repeat({"x"},_{1}-_{0}+1)),
    Custom3 = List.Transform ( List.Split( List.RemoveLastN(List.RemoveFirstN(List.PositionOf( Custom1, "x", Occurrence.All), 1),1), 2), each List.Repeat({"y"},_{1}-_{0}-1)),
    HelperColumn = List.Accumulate ( List.RemoveNulls(List.Union(List.Zip({Custom2,Custom3})) ), {}, (s,c)=> s&c ),
    NewTable = Table.FromColumns( Table.ToColumns(Source) & {HelperColumn}  , Table.ColumnNames(Source)&{"Helper"}),
    Grouped = Table.Group(NewTable, {"Helper"}, {{"A", each let t=_ in Table.AddColumn ( Table.AddColumn(_, "Type Of Change", each if [Helper]="x" then "Part of Sync" else "Non Revision sync" ), "Sync ID", each List.Max (t[#"Previous Value"])), type table}}, GroupKind.Local),
    #"Expanded A" = Table.ExpandTableColumn(Grouped, "A", Table.ColumnNames(Source)&{"Type Of Change", "Sync ID"}),
    FINAL = Table.RemoveColumns(#"Expanded A",{"Helper"})
in
    FINAL