Bulk Renaming Columns after Splitting by Delimiter

You can use this where #"Split Column by Delimiter" is last step and it will generate names like "ID","Permit Ref","EndDate", "ID1","Permit Ref1","EndDate1", "ID2","Permit Ref2","EndDate2" and so on. It is not dependent upon how many columns do you have

= Table.TransformColumnNames(#"Split Column by Delimiter",(x)=> if Text.Start(x,5)="data." then {"ID","Permit Ref","EndDate"}{Number.Mod(Number.From(Text.AfterDelimiter(x,"."))-1,3)} else x)

 See the working here - Open a blank query - Home - Advanced Editor - Remove everything from there and paste the below code to test (later on when you use the query on your dataset, you will have to change the source appropriately. If you have columns other than these, then delete Changed type step and do a Changed type for complete table from UI again)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("DY6xEcMwDMR2cY1CzycpaRafi+TiBbx/ER8KlMB5Hr/7OTju5+X1hy8mKZrJYqOBhAIZJSrUaKKFNjEIEUGYSKKIJiaxiI0HFg5snLhw44kX3uQgRQb5FpMssslJLnJTgxIVlKl3qKimJrWoTQ9adNCm87iuPw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ColA = _t, ColB = _t, data = _t]),
    #"Split Column by Delimiter" = Table.SplitColumn(Source, "data", Splitter.SplitTextByDelimiter(",", QuoteStyle.Csv), {"data.1", "data.2", "data.3", "data.4", "data.5", "data.6", "data.7", "data.8", "data.9", "data.10", "data.11", "data.12", "data.13", "data.14", "data.15", "data.16", "data.17", "data.18", "data.19", "data.20", "data.21", "data.22", "data.23", "data.24", "data.25", "data.26", "data.27", "data.28", "data.29", "data.30", "data.31", "data.32", "data.33", "data.34", "data.35", "data.36", "data.37", "data.38", "data.39", "data.40", "data.41", "data.42", "data.43", "data.44", "data.45", "data.46", "data.47", "data.48", "data.49", "data.50", "data.51", "data.52", "data.53", "data.54", "data.55", "data.56", "data.57", "data.58", "data.59", "data.60", "data.61", "data.62", "data.63", "data.64"}),
    Custom1 = Table.TransformColumnNames(#"Split Column by Delimiter",(x)=> if Text.Start(x,5)="data." then {"ID","Permit Ref","EndDate"}{Number.Mod(Number.From(Text.AfterDelimiter(x,"."))-1,3)} else x)
in
    Custom1