It's interesting see people still working in this niche, I think it used to be called "backend as a service"? There were several contenders at one point, but Firebase seemed to "win" several years ago, and has been the last one standing for some time. Just curious what the market size is for these types of services? It doesn't seem like anyone really uses them; for tech people it's just as easy to spin up an instance…
It's closed source and locks you into Google Cloud.
You can't self host. And since it's pay for use, you can end up with large unexpected bills for a variety of reasons.
It doesn't have full text search.
It doesn't have a relational database.
I'm sure there are more things. Firebase is awesome but it's definitely not the ultimate solution.