Google Adsense is retiring its Adsense link ads as of March 10, 2021. Adsense long ago has been trashed by adblocking so it took this long to be retired is amazing. Google still owes the studio some cash.
The refuge of commision based Amazon ads was augmented by an experiment in CPM ads that lasted about 12 months before it was retired. The CPM rate was as low as 2 cents which amounted to a few dollars per month for the site at best.
Google has other ads but the same old problem of limited earnings even with heavy traffic. In 2000, the paid to surf early was by far the biggest income stream the site ever enjoyed. 20 years onwards the site remains albeit its content is substantially larger.