Weird huge size loading

There are 2 data sets,

Set1 is a single excel table, contains about 7000 rows 3 columns, size 164KB. 3 columns. ALL are text.

Set2 is getting data from local disk folder, 19 excel files, 141MB in total. Each file contains about 180K rows, 8 columns.

Contains Date, URL, Keywords, Impressions, Clicks data.

Trim, lowercase are applied to column URL, then a custom column is added, to search if a any value in [URL] contains any value in another column in Set1 and returns the contained text.

The M is:

=let myvalue=[URL]
in
Text.Combine(
Table.SelectRows(Keywords,
each Text.Contains(myvalue,[Terms]))[Terms]
,
",")

But after I click transform and load, the Power BI loading it for even a hour and displaying, and it is still loading with increasing size

The file -deduplicated.xlsx is the one only has 164KB size.

Anyone could help to advise the reason and how to resolve this?

Thanks in advance.