It sounds like you were running a production workload on the Hobby plan
your company's mod in that thread said there was supposed to be no SMTP at all for any plan but it was enabled by a bug. then once you saw people were using it you decided to milk your bug via the most expensive payment plan.
but that's your internal dealings. from your paying customers perspective, company had a change in the environment where something was working and now it's not. which could be even okay if it was a legit bug that was fixed, but what makes it worse is instead you said "just pay us 4x more and you get it back". for some users it probably just broke production, is there a more perfect time for blackmail right?
don't try to paint it as altruistic attempt to reduce spam in the internet, this is sleazy af
You know, the same country whose former prime minister is this person: https://jmail.world/person/ehud-barak
Made the mistake. Never again.
Fly, railway, render. Avoid. All have weird show stopper bugs for any reasonable scale and you will fight against the platform compared to using big cloud.
And big cloud works better even in cases where PAAS is advertised as simpler (google cloud run and build is as easy to setup as railway but you have much more knobs to control traffic, routing, roll out etc)