It feels like a bait-and-switch and the "heroin dealer" model to give something away for free just long enough that people become reliant on it, and then suddenly make it be paid.
Heroku's free tier has been incapable of running a 24/7-accessible webserver for many years, nearly a decade[0].
At this point, if anyone is reliant on it, it's almost impressive that they've managed to get by for so long without either paying Heroku or bouncing off to another service.
[0] if you give them a verified credit card, you get a few additional free hours per month, just barely enough to run a single webserver full-time on one dyno. At best, the free tier offering is... incredibly limited.
I would say this kind of free tier is quite powerful. It even had free Redis and PostgreSQL. But it had some horrendous periods of downtime and bugs that affect the paying customers just as badly. So ironically the free Heroku experience in 2022 leads you to the conclusion that it's the worst service you could pay for, but the best service you could mooch off of (aside from fly.io and similar) -- which may be counterproductive for Heroku's marketing.
What does Heroku / Salesforce owe us?