To mail you documents related/associated with your employment? Not really unheard of to receive 401k/insurance/other benefits mail. Also, taxes and tax documents like W2’s
Potentially background checks? Maybe? Otherwise yeah it’s a bit weird and more information than they really need.
Overreach in data collection is everywhere these days sadly… far too many things are not properly considered PII (personally identifiable information) even though multiple things in aggregate could completely doxx a person.