In case you’re asking in good faith… The downside is that non-citizens voting is simply not a problem. The number of cases is extremely low, there’s nothing to “fix” here. The biggest impact of this policy would be that actual American citizens who do not have, or lost, or forgot to bring their proof of citizenship will not be able to vote. It will predominantly affect poor and marginal populations. People that don’t have a passport, don’t have easy access to their birth certificate, or aren’t aware of the new regulation. Fewer people voting is 100% the goal with this policy.