This is the same issue reported in #28934, but for the inplace multiplication. The fix there does not seem to include rmul! and lmul!, as far as I can tell.

EDIT: Now I'm confused. Are there instances of rmul!(A::SparseMatrixCSC, D::Diagonal) and lmul!(D::Diagonal, A::SparseMatrixCSC) to begin with? I can't seem to find them. In case there aren't, is that on purpose?