It sounds to me like you really care about mentees being successful and are investing a lot of time/effort. I believe you can change your outlook a bit into knowing it's moreso on them to flourish. For example, you sound extremely hands-on for a mentor. I would not do all of their coding for them.

IMO it's not your job to teach how to use a framework. But instead of assuming they "should" know things, you could assume they are skilled but at different aspects of development. So from this perspective, a mentor might give additional topics to brush up on to be successful in the job. And still be super open to providing internal career advice, helping with company-specific things, etc.

It sounds like maybe a lot of what you write here is important for mentee success yet not being communicated. You could probably be more upfront about team expectations, and let them know what a typical dev workload will look like.

Hiring is tough, and some people are not able to perform as well as expected. That can be frustrating, but it's not your fault. You may want to clarify how the company evaluates new hires so you know the process.