An amazing tool adding a great deal of value to YouTube. If I could only donate to one project I would choose this. Shame on me I can't in fact even find how do I donate to this.
Not sure how this might (not) be presented in other contexts, but when I go to the main repository page on a desktop browser, there's a "Sponsor this project" box in the rightmost layout column that links to a Markdown file with Ko-Fi and/or GitHub Sponsor links for the individual maintainers [1].