white squares on certain models using Brixel

I can't replicate this rn with a different resource pack. This happens to me with BSL and SEUS PTI. For some reason this doesn't happen with Continuum. no shaders with both optifine and iris have this square just black for optifine and grey for iris. pictures are iris bsl, optifine bsl, iris continuum, iris no shaders and optifine no shaders mc 1.20.2 quilt 0.21.2 sodium 0.5.3 iris 1.6.10