Just as the name suggests, UltraQLC is not a type of memory per se, but a mix of Sandisk's BICS 8 QLC 3D NAND, a very advanced proprietary controller with a whopping 64 NAND channel, and firmware.

We bumped up the minimum capacity we recommend from 64 GB to 128 GB for SD cards ... write speeds from UHS-I cards that have DDR memory in them (SanDisk brands this feature as QuickFlow Technology).