It depends on UE capability.
See this:
maxNumberMIMO-LayersCB-PUSCH
Defines supported maximum number of MIMO layers at the UE for PUSCH transmission with codebook precoding. UE indicating support of this feature shall also indicate support of PUSCH codebook coherency subset. This feature is not supported for SUL.
maxNumberMIMO-LayersNonCB-PUSCH
Defines supported maximum number of MIMO layers at the UE for PUSCH transmission using non-codebook precoding. This feature is not supported for SUL.
But you are right…I have checked 2-3 logs this param is always 1 layer for UL MIMO.
Probably on S21 Samsung is different.
Or Iphone 12.