I haven't worked at Google, but I have worked at a very large tech company, and this isn't accurate.
They still hire frontend devs. Those frontend devs still do front-end JS with libraries. Some of them work on in-house libraries, but their focus is still narrow. Same for backend - they use the industry standard term to mean the industry standard.
However, the differentiation of teams/departments is much higher. To take on your argument directly, a project to create a new database would have software engineers but be on an infrastructure team. They don't call themselves backend engineers or recruit backend engineers, they call themselves software engineers and recruit people with skills writing system software.
They still hire frontend devs. Those frontend devs still do front-end JS with libraries. Some of them work on in-house libraries, but their focus is still narrow. Same for backend - they use the industry standard term to mean the industry standard.
However, the differentiation of teams/departments is much higher. To take on your argument directly, a project to create a new database would have software engineers but be on an infrastructure team. They don't call themselves backend engineers or recruit backend engineers, they call themselves software engineers and recruit people with skills writing system software.