What has been your biggest challenge working as a TPM?

I personally enjoy my role. I think no challenge is insurmountable. If I were to think hard, especially at Meta, the pace at which technology advances is simply astounding. Especially in Integrity (a.k.a Trust & Safety) domain that I lead, the complexity of adversarial problems and the AI/ML investments we make to solve for those, is staggering. As a people manager I need to be deliberate about keeping myself up to date and grounded in my area of ownership.

The biggest challenge for any tech product manager (or program manager) will remain your ability to influence. You need to influence members at all levels of the organization on whom you have little authority. 

The way to overcome this is ensuring your have a clear understanding of why your work/request is important. You would also need to ensure that the recipient finds these important and it is aligned with some goal of their own.