Correct premise: many FOSS projects need money.
I recently unblocked Carbon Ads on regex101.com (which is not even open source, but the site asked so nicely, and is so good). Now I'm wondering if Carbon is still an "ethical" network. This popped up prominently in a related search. Sad that Codesponsor seems to be down, and that Triplebyte has made a controversial pivot in 2020.