Unsurprisingly, data egress to third parties is a major security vector - especially for mission critical jobs like working in the House. MS apps incorporating Copilot have faced similar blocks as well.
This requirement for data stewardship is called out in HITPOL8 as well [1][2] (the AI tool standards set by the House CAO).
[0] - https://faq.whatsapp.com/203220822537614/?cms_platform=iphon...
[1] - https://cha.house.gov/_cache/files/4/2/42dca19e-194b-481e-b1...
[2] - https://cha.house.gov/_cache/files/0/8/08476380-95c3-4989-ad...