The background of my homescreen keeps changing and I do not know what causes it. I can change the background manually, but after a certain moment of time it just changes automatically to another background. It is really annoying. I mean... I do not hate baby's. But I do not want them randomly eating biscuits on the background of my phone 🧐.
An app must have the permission
android.permission.SET_WALLPAPER to change wallpaper. I suggest you find out which apps have that permission and than try to disable or remove some of those app one by one until you no longer have that problem.
You can use a permission checker app to find those app. User Izzy maintains a nice list here if you need help finding one. I have used aSpotCat earlier so I'm showing you how you can use it to list all the apps having that permission.
Launch the app.
Choose List apps by permission
Scroll down and choose Misc. Permission
Tap the three horizontal line icon next the Misc. Permission to list the permissions instead of the apps.
In the search bar (tap the lens icon) type
Under Set Wallpaper category you can find the apps which have the permission to change wallpaper.