array to filter

In Power Query, just split this column by the comma delimiter into rows, then remove duplicates. Here is the code:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WSlSK1QGSOkk6yWAWjAaKxwIA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column = _t]),
    #"Split Column by Delimiter" = Table.ExpandListColumn(Table.TransformColumns(Source, {{"Column", Splitter.SplitTextByDelimiter(",", QuoteStyle.Csv), let itemType = (type nullable text) meta [Serialized.Text = true] in type {itemType}}}), "Column"),
    #"Removed Duplicates" = Table.Distinct(#"Split Column by Delimiter")
in
    #"Removed Duplicates"

Turns this:

into this, which can be used for your slicer.

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.