Possibly I'm a horrible conversation partner, but even today already it happens with some regularity that someone is checking their phone while I'm in a conversation with them. It's even more common in group conversations.

And tacking on some personal experience, I've also noticed when I'm meeting over Zoom (i.e. with the rest of the internet within arm's reach), I get distracted way more easily than when meeting in real life. Sure, maybe not all those meetings are super important to me, but I'm not sure if the world would be a worse place if that wasn't possible.

I try to put on a friendly tone and say "I'll continue once you're done with whatever you need to do on your phone". Sometimes it really was something important (the last few seconds of an auction is the common, time-sensitive case) but most of the time they realise the faux pas they committed and are apologetic about it.