The S21 Ultra's upper speaker's hole is actually tiny! I was taking a closer look at the earpiece speaker slit when I suddenly noticed that the slit is actually mostly empty, save
Amazon.com: Home Theater Sound Speaker Bluetooth Slim Custom Case Cover for Samsung Galaxy S21 Ultra S21+ S20 FE S10 Plus S9 : Cell Phones & Accessories
Samsung Galaxy S21 Ultra VS Galaxy S9+ Duel Stereo Speakers Sound Quality Test Which is Loudest - YouTube