My understanding is that "tech lead" as a role in Big Tech is more of a gateway position to bridge the gap between IC and management roles, a transition for a well-performing engineer who otherwise has no experience managing a team to "bootstrap" and gain that experience. During this, coding expectations for said engineer naturally lowers, and is shifted towards the total productivity of the emerging "subtree".
I think there are probably almost as many definitions of tech lead as there are companies. In my case the tech leads in the company are responsible for turning high level requirements from the rest of the company into actual actionable work, and feeding back up to senior management places where we could improve the existing product by refactoring/introducing new features. Alongside that we do line management for the people on our team, and generally act as a point of contact to try and reduce the level of interruptions to developers.
It’s very much not an IC role - we might throw together the odd prototype, and we’re all very capable of rolling our sleeves up and helping out if a project needs an extra person for a bit, but the general rule is that if we’re on the critical path for implementing a project something has gone wrong.
This sounds like a Product Owner to me. Indeed, all these types of roles are pretty much interchangeable depending on the exact structure of your teams.
From my cynical experience it's a way to "reward" individual contributors with a meaningless title to make them feel like they are advancing their careers. It's purely responsibility without empowerment. In my naive days I was told I was a "tech lead" and I was very proud until I realized this meant being a scape goat for project's misfortunes without having the ability to schedule other people's time and thus materially change the way things as opposed to being the midnight oil superhero. Since then I never accepted such nonsense.
Make me a proper leader with the ability to truly delegate and alter scope, workload and the timing of work or pound sand.
At my org "lead engineer" is a seniority title. The people you look for are the maintainers and core contributors- the people with access to approve commits, and the people who are highly active in design and code review.
Didn't mean to suggest that it should be zero— only that new leads feel like they are falling behind when they're actually doing normal leadership tasks, because it's not coding, and coding is what feels like work to them; or that their instinct for dealing with increased workload is to code more (instead of organizing more). Those are bad instincts, hence they need to readjust their definition of "what feels like work".