The sad reality is over past decade I have not seen a single source of online revenue that has remained consistent for small businesses, which is what many writers are. Facebook, AirB&B, Amazon, Gumroad, the list goes on. Once platforms feel they have an invested user base they monetise them every way they can through reduced earnings, increased fees, paid for search results and more.
When Facebook decimated organic reach and introduced paid boosts it destroyed many a business.
Many, many of us hoped Medium would be different. Time will tell.