I also have a messaging feature in my app, so I know exactly what’s happening for you.
This is caused by a serious Bubble bug that they have ignored for years. Their elastic search functionality breaks on iOS mobile browsers whenever the window is closed. The bdk wrapper uses a frameless safari instance to display your app, so the same rules apply.
I have been able to work around this somewhat by adding a date search parameter to all searches that I need to keep updated. I have the app change the date for the parameter every time the user interacts with the app. This changes the search enough to force Bubble to reset and re-establish the connection to the server. See screenshot below.
You could also tie this to a refresh button or any other action in the app. Just keep in mind this does force the RG to complete reload content, so you don’t want to change the parameter unless necessary. Not a perfect solution, but better than having to reload the page every time you open the app.