From the same article:

And a review of public records suggests he may have had divergent political leanings, with Crooks registering to vote as a Republican but making a small donation to a Democratic-leaning group.

Federal Election Commission records show that a donor listed as Thomas Crooks with the gunman’s street address gave $15 to Progressive Turnout Project, a Democratic-aligned political action committee, on Inauguration Day in January 2021, when Crooks was 17.