What I mean by "Tech Lead" role and responsibilities
It's the person who is responsible for the technical quality of the project. For example, the Team agrees to adhere to a particular level of quality (e.g no linter errors, no failing tests, naming conventions, Git branching model, release cycles, modular structure, software design practices and principles). The Tech Lead is the person who detects violations of our quality policy, communicates it to team members, and explains what should be improved.
Tech Lead has a high-level vision of the project architecture, and also aware of low-level details and nuances, by being involved in everyday development activities.
Tech lead spends 80% of his time in development activities. Otherwise, he will lose the technical feeling of the project, and become a "Сферический конь в вакууме". In the same way, Tech Lead is not limited only to tech debt or infrastructure-related tasks, he works on regular product