> there will be few-to-none signs of subversion

One thing the Estonian system does is that you can verify your vote on a mobile device by scanning a qr code that you see when you cast the digital vote. A vote can be checked after i-voting for up to three times during half an hour.

I imagine if any mismatch was detected the country would shut off i-voting immediately.

Further reading: https://www.valimised.ee/en/internet-voting/checking-i-vote