Bad tech leads take the high-profile tasks for themselves and are motivated by being able to take credit for doing the work. They optimize locally, keeping team members working on projects that benefit the team at the expense of the engineering organization at large.
Good tech leads listen and encourage debate. When the team is unable to resolve a debate, they describe a process or framework of thinking that would help them resolve it. They don’t enter discussions with foregone conclusions, and always allow themselves to be persuaded by great ideas.