I never load CUDA, actually.
First, ssystem("processor full"); gives nothing useful : [-1, ""]
I am pretty sure the problem comes from matrix multiply in both. As I said, the crash does not occur until the last line, in the question. Of course, a failing SVD /could/ leave Maple in an unstable state, but I have exactly the same problem with vv's code hence (without SVD), so it's plausible.
I already mentionned I have an i7 9700F. Windows tells me:
Intel(R) Core(TM) i7-9700F CPU @ 3.00GHz, 3000 MHz
It has 8 cores.
OMP_NUM_THREADS is not defined by default. When I set it to 1, the code does not crash anymore (both the original problem in the question and vv's code). It still crashes if OMP_NUM_THREADS is set to 2 or 4.
However, it may be worth telling again that Maple 2020.2 does not crash, with or without OMP_NUM_THREADS.
I also installed Intel oneAPI (after I noticed the bug, so no interaction here), and a simple Fortran program with DGEMM works like a charm. Of course this proves nothing, Maple has likely another version.
Anyway, the fact that the very same code works on the same machine in the same conditions with Maple 2020.2, and crashes with Maple 2021.1, seems a good indication that there is something wrong in the latter. It may be a problem in MKL, and setting OMP_NUM_THREADS definitely helps.