When doing a search request on https://search.icons8.com/api/iconsets/v5/search and use the “Api-Key” header for authentication instead of the “token” URL-parameter, a “message” property will be included in the resulting json.
“message”:“Caution: you are not using an API key. It’s OK for now, but please get one at https://developers.icons8.com. We switch off the anonymous access on January 1, 2021.”
IMO the search should work with the “Api-Key” header and no warning should be included.