Firebase is super convenient and works very well for the most part but my heart races every time I receive an e-mail from them. A silly mistake can cost you so much money and they tend to word the e-mails strongly.
They tend to word emails strongly to affect action.
As for the cost overruns: I don't know anyone who wrote one of those blog posts (or emailed support) who didn't get their bill refunded.
We can argue about spending caps or hard limits (which people generally dislike for their production apps), but the people side of the business is (or at least was) solid.
Source: worded emails strongly to affect action at Firebase and refunded a number of bills.
Firebase does have some issues but the core premise is solid and IMHO everything will be like that as we go forward.
I might be speaking as a jack of all trade so it seems easier to me. For a frontend only dev who needs a backend it might be different.
I agree in general: I choose netlify/vercel over S3+lambda or vps.