I'm going to ask my parents to stay off their phones when we spend time together
Are you parent's always on their phones?
They usually check their phones whenever I'm talking to them.
You should tell them to stay off their phones because if you are spending quality time together as a family it should be family time only. Otherwise, what's the point of spending time together. You could have gone off doing other productive things.
I just want the not be so distracted when they are with me.
And that is totally fine o feel that way. Pointing out your parents' inconsiderate actions isn't wrong.