Common ways this happens? They are using a credit card to run their business with no backup payment method. Then the company's contact person is on vacation.
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Railway hosts applications for customers. An uneducated guess for some possible reasons: 1) one of those customers hosted something they shouldn't have 2) railway had something spawn that took up too many resources 3) Or their account balance was too high 4) Or something...
But all of this probably culminates in someone needed to read an email that was missed.
Scaling a customer infrastructure setup like Railway is hard. This is one of the non-technical hard parts - how to make sure your account with your primary vendor is safe. But, I'm willing to wait to pass judgement here until more information is available. I'm sure the post-mortem will have lessons. I'd like to know more.
If it's anything like AWS, that may be just one of hundreds of emails they send every day, most of which are just noise.