My county is sent out a flyer saying “check your registration.” I did and it’s good but why would they do that? I believe it’s because they know left wing voter registration groups rip up entries for Republicans or Libertarians.
...or they want to track whom checks their registration, those that don’t may be unlikely to vote - so you can vote for them.
Sometimes voters who registered, but have not voted recently (time varies), will be dropped from the rolls. If you check your registration, you’ll know ahead of time and can take appropriate action. Especially in states that do not allow same-day registration.
They are probably getting ready to do a purge of the list. I know in my town if you do not vote for a few years they will purge your name from the list.
If they touch base, and you go to check it, it probably keeps it “alive”.
I doubt if they are looking for anything other than dead people and kids who have moved out.