The webcomics I work for have their own authors.
In Addie's case with Scarlet Society we make... $2 monthly through Patreon, we also have a Ko-Fi but nothing much happened there
In SizzleGames case with Yandere City, there is no income so far since the series is in development
In OfficialGenesis. Love Quotes (BL) probably has made an income but she is a writer and also has a Patreon where she makes exclusive content of her other series as well
Then, GIRI and Solomon's Time have received one time supports during the time I was making the comic before the Webtoon Contests they were created for.
But most of my income comes from making webcomics for others, working as an assistant from time to time, being hired to make exclusive content for other people's Patreons or simply doing art commissions. Every year I receive around $20 from RedBubble despite I barely post new designs in there.