My mom's phone (a galaxy model) has developed the issue that randomly, ads will show during normal use which are not connected to the app being used. The ads occupy the entire screen and can be closed by clicking an X mark in the corner. If this was a computer, I would assume a virus/adware or some other malware, but I've never heard of this on an android phone.
I uninstalled all apps whose purpose was doubtful, but still the issue occurs.
How can I figure out which piece of software is doing this, preferably without downloading the developer tools on my computer and figuring out which logs to search?