I'm surprised so many replies here are about removing a free tier 2 years ago. Things cost money, what did you expect? Whenever I get free products that cost money I expect it's either temporary, or I'm being the product myself.
So? Maybe don't offer a free tier if you can't sustain it? And many other providers (like Neon, Koyeb, Supabase etc) still offer a free tier. Personally I don't like this type of bait and switch. If you can't sustain something don't offer it in the first place. Same with open source projects going closed source for money after getting free work from open source programmers.