A while ago, a patent lawyer was filing a patent application for me and a few others to the USPTO, and they asked us for our citizenships. I wonder why. Does the inventor's citizenship have to be indicated when filing a patent application to the USPTO? I don't see it in the USPTO Application Data Sheet.
For national applications - Yes, before the AIA, no after the AIA. So currently no.
Separately, there are issues involving PCT applications. You can only file a PCT application in a location where at least one inventor or assignee has a citizenship or residency.
As a US citizen (and patent agent) I can file at the USPTO for a group of Canadian inventors working for a purely Canadian company by becoming “an assignee of convenience”. For example giving me (or any other US Person) the rights to the application in Luxembourg. Later they/we can decide not to follow through with entering into the nation stage there. Sounds crooked but it’s not. The official PCT seminars cover it.
Separately the trademark side has been floded with bogus trademark applications from China. Normally you can file a trademark application yourself (may not be wise, but allowed). A new rule says you need an attorney in the US to file a trademark application if you are not from US.