It's perhaps worth saying that if you must mix OpenMP libraries built against the LLVM (Kuck/Intel) runtime, and GNU GOMP on GNU/Linux: Ensure libomp is built with GOMP compatibility, however that's configured, make a shim from the result, like

    gcc -shared -Wl,-soname=libgomp.so.1 -o libgomp.so.1 empty.c -lomp5

where empty.c is an empty file, and put the result on LD_LIBRARY_PATH ahead of the real libgomp. Alternatively, preload the compatible libomp5. On Debian 11 there's already a libgomp in the llvm packaging. Dynamic linking assumed, as is right and fitting.