What causes apps to close on one iPhone when locked but stay open on another?

I have two iPhone 14's (one is mine, the other my daugther's). This issue has been happening while both were on 18.7.1 (I have since upgraded to 26.0.1 on my phone. When I have an app open, then lock the screen, the app closes on my daughter's phones, but the same exact scenario on mine, the app doesn't closed.

I created the same shortcut on both:

When this app closes > Turn the flashlight on (irrelevant, just a signal if it closes or not)

Same app, all the settings that I can find are the same, yet, when I do the exact same steps, there are different outcomes. I also can't reproduce the issue on my phone. I've tried all the power settings, standby, background refresh, low battery mode, everything. Yet, nothing works. Not only can I not get the app to stay open when I lock the screen on my daughter's phone, I can't get it to close when I lock the screen on my phone.

Does anyone know a way I can see a list of settings from each phone so I can compare side-by-side, or something else that could help me figure out what is the difference between the two that would render a different outcome? I've been spending hours on this, and can't figure it out.

I should add that, I've tried multiple apps, and the outcome is the same. It's not app-specific. The only apps that stay running while the screen is locked, are apps that stream, such as music.

[Re-Titled by Moderator]

Original Title: App closes when phone locked on one phone, but not another