I've interviewed hundreds of people over my career and I've never had an interview where I couldn't figure out their technical abilities through a conversation.
I'll tell you what leetcode interviews do find you though, they find you people that have no idea how TCP/HTTP work, they have no idea how you would debug a distributed system. They've never deployed anything to a server. They probably have no idea how to even measure the amount of work being performed by a server. They've never thought about CI/CD/Deployment/Scalability. They've never used any cloud resources. They have potentially never been through a code review.
etc, etc, etc, etc.
Someone crushing a leetcode test tells me about 1% of the stuff I'd like to know about their knowledge and abilities.
Some solutions are rejected on the spot (bad practices, does not solve the task correctly), other candidates are invited for a technical interview. Some generic questions, then we go through the solution - with emphasis on less than perfect areas. It is quite easy to see when someone is bluffing, and you also see how the person deals with feedback.