If the business case doesn't require partner/3rd party API access, then maybe Firebase is appropriate.
Mentioned elsewhere in the comments here is the risk of vendor lock-in.
Given Google's history of EOLing products from under developers, there is real risk in putting all the business logic eggs in the Google basket.
It gives easy to use serverless CRUD (with Firestore), authentication, authorization, secure file upload, hosting and server-side functions for things like image processing or database triggers.
I don't think Firebase will be end of live anytime soon, worst case it's user base would get migrated to Google Cloud, as it's really just Google Cloud under the hood. I don't think it's an option for Google to give up on the cloud at this point, even though AFIK Amazon has the biggest market share.