Oh my gosh yes. I’m a stepmom who lurks here to try to understand where SO and his ex are coming from so feel free to downvote me cuz I’m not a single parent. But YES the kids act like informants sometimes.
Your kids’ future stepmom will GREATLY appreciate if you work to decrease this, and you’ll probably avoid a lot of unwanted/unneeded conflict - kids are reeeally bad informants it turns out! I’ve been abusive, pregnant, cheating, etc. according to the kids so do keep in mind they’re not always even accurate!
What helped decrease it for us is basically acting kind of uninterested. Once the ‘here’s everything we did last week report’ starts we’ll interrupt and go cool, that’s nice, want to play video games? Or whatever will distract them.
When it’s something they’re upset about, we’ll either say do you want us to talk to Mom about this or you should talk to Mom about this (basically try to leave it between the other parent and the kid).
And we neeeeever ask follow-up questions. Five years in, it’s diminished a lot.
Also, I grew up in a split household and I remember doing this to my parents. I was just trying to share because they weren’t there and figured they wanted to know. Usually I don’t think there’s much harm in it (until steps enter and the kids try to divide and conquer, which is a different game).