By now most everyone has heard of the ATF's Proposed Rules to reclassify firearms and parts. If not, a quick Google will reveal much more information that I could possibly type today.
It is now time for the public to comment!!!

(Link also has complete text of the proposal)

https://www.federalregister.gov/documents/2021/05/21/2021-10058/definition-of-frame-or-receiver-and-identification-of-firearms#open-comment