I'm personally very wary of using algorithms questions as a proxy for how "adept" someone is at software engineering. If I were running a business, I'd personally want to make sure people could manage technical debt and build decoupled systems.
I have had multiple positions at FAANG companies, and despite being "adept" according to these algorithms questions the systems built by these highly-paid (and, around me, generally experienced) people are pretty awful in terms of quality and maintenance.
Learning a proprietary stack also hampers effectiveness in future positions if wanting to opt-out of FAANG later on.