General Discussion

with voter registration systems* (ND does not have a registration system).
https://ballotpedia.org/Proof_of_citizenship_requirements_for_voter_registration_by_state

Alabama, Arizona, Georgia, Kansas, Louisiana, New Hampshire, and Wyoming — have laws requiring proof of citizenship at the time of voter registration. The other states merely require you to sign that you are a citizen--not show proof via a passport or certified BC--under penalty of perjury.

With the advent of REALID driver's licenses, recipients will have demonstrated proof of citizenship or eventually will when their licenses renew, but not all Americans have driver's licenses and not all (yet) who do will have the REALID certification.

Plus if you registered many decades ago, states do not make you re-register unless you move outside the precinct.

But, yes, any changes that require proof of citizenship to VOTE (with a valid registration checked against some form of id) at the point your ballot is accepted will destroy voting systems--all of them, but especially mail-in.