I think it’s because LinearAlgebra has been moved into the standard library?
Anyway, a few possibilities if you want info regarding your BLAS library:
julia> using LinearAlgebra
julia> BLAS.vendor()
:mkl
julia> Base.libblas_name
"libmkl_rt"
julia> using Libdl
julia> Libdl.dlpath(Libdl.dlopen(Base.libblas_name))
"/home/chriselrod/Documents/languages/jdev/usr/bin/../lib/julia/libmkl_rt.so"
EDIT:
julia> BLAS.openblas_get_config()
"USE64BITINT DYNAMIC_ARCH NO_AFFINITY Zen MAX_THREADS=16"