Every so often when I pick up my S21 there an odd screen greeting me. It has a large square in the center with an arrow in it, and below it says "download." Some English text on how to cancel and some Asian text. If I mess with the screen it changes to a number of barcodes.. The phone will usually reboot. A friend thought it might be a firmware update, but I have no idea.
@usercoO7rYlCli Sounds more like some sneaky app is pushing spammy pop ups on you. Review your recently downloaded apps, and maybe try removing them and installing one by one to figure out which one is doing it.
Found out what it was. I keep my phone in a holster and when taking it out, my thumb has the potential of hitting the volume up and down and the side button at the same time. Doing that puts you into the mode to allow you to put a 3rd party OS in. It's no bad app or virus, just a function of the phone.