Yes, TCC is what I meant, but my understanding is TCC is a platform wide sandboxing system?

TCC is a leaky shoot at limiting non-sandboxed apps permissions. The actual macOS sandbox is a different thing.

I would say that TCC is working as intended, unfortunately, with many obscure behaviors to avoid breaking existing apps.

It's even more unfortunate that a lot of apps that could be easily sandboxed aren't.