+1, 1401 is buggy if your not running default settings.
After hearing about all the stability issues folks were having after updating from 1302 I was hesitate to try 1401, but reading the change log for 1401,.. I was interested in seeing improved memory overclocking, and adjustment of the Tjmax parameter when using i9-9900KS.
Before updating I was 100% stable at 5.3GHz 1.35V, and running 4600MHz memory in XMP mode. With 1401 same settings are unstable and memory will not boot in XMP at 4600MHz. So not sure what they mean "Improve Memory overclocking rules"
I spent a few days running CPU @ default settings, and 2x8GB memory at 4133MHz with no issues 100% stable, I tried 2x16GB 4000MHz memory kit and could not boot in XMP or manual settings, and same 2x16GB kit worked fine with 1302 BIOS in XMP mode.
For my system the 1401 BIOS does not offer any performance improvement, memory overclocking is also not improved.