I don't know if the problems are linked or separate. My S25 Ultra will occasionally freeze up.  The touch screen will not respond. If I press the power button, it will return to the lock screen, and I can log back in, but it still doesn't respond. I can't sweep down from the top to access any menus. I can press and hold the power and volume up buttons and either power off or restart the phone. Once it restarts, everything works normally.

The other problem is that the phone randomly buffers. I have 4 blue squares in the center of the screen that rotate around in light blue and darker blue shades for several seconds, and then, the normal functions return.