Samsung's foundries have struggled for the past few years to achieve their targets, whereas TSMC has continued improving at their projected rates. TSMC's process is now significantly ahead of Samsung's, such that the same designs are better on TSMC. These improvements are along the lines of fewer defects, higher switching speeds, less leakage, etc.

The Snapdragon 8 Gen 1 was made on Samsung's fabs. The 8+ Gen 1 is the same design on TSMC.

To be clear, this is for Samsung's processor foundries. Their DRAM and flash memory still appear to be industry leaders.