Policy where I teach is that it's up to the professor's discretion, though that's mostly because it's not always as easy to prove as this. There's a boilerplate anti cheating section we have in our syllabus that says it's a reportable offense that may lead to academic probation or expulsion.

Honestly, it's also a ton of paperwork so I've just opted to fail them since usually my papers aren't so easily answered via an LLM and rather than tell them I caught them cheating, I simply point out they missed rubric item 2, 5 and 6 so it's something solid, not my speculation. But I also haven't white texted them yet, lol.