Is it common for some timings to lose stability after BIOS updates?

I was banging my head against the wall and couldn’t understand why my 6400 profile became unstable after switching to the newest BIOS(Version 2004, on X870E-E Strix). Turns out it’s tRCD (read) – I never had any issues running it at 36 before, but now it needs to be set to 38.

With [THIS](https://i.ibb.co/WwVLPnM/image.png) configuration (and 2200FCLK) I passed 4h+ of y-cruncher, 6h+ of TM5 Absolut, 12h+ of Karhu, and earned OCCT golden stability certificate. Now, with this BIOS, 36 tRCDRD shits the bed after min of y-cruncher.

I always thought it was more dependent on the DIMMs rather than the BIOS.

Thoughts?