So...What do you think about checking each others phones?

Is it toxic lol? Many people say you shouldn't do it because it's a sign that you lack trust. But I also feel like it's a double entendre because let's be honest. If you have a problem with your partner exploring your phone, doesn't that mean you have something to hide? Idk. What do you all think? My ex and I didn't have this issue. He had an android, and I had an iPhone. So we would use each other's phones for different reasons. We had each other's passwords to everything as well. Out of human nature/curiosity, we've both gone through each other's phones lol. Albeit it was only once or twice. I personally don't like people going through my phone because my search history is a little wild. Not going to lie...