That looks exactly like the wire management mesh that came with my Ikea IDÅSEN desk. I think the desk in the picture may be an Ikea BEKANT. See the fourth picture here (link might break if you select one of their non-US sites):
https://www.ikea.com/us/en/p/bekant-desk-white-s19006323/I guess they don't sell the net separately, its held on by snap-in plugs that require specifically sized holes in the desk top IIRC. Maaaaybe you could look for a part number in the Bekant/Idasen instructions and ask nicely at their customer service desk if they'll sell you just the net?
FWIW, the IKEA nets actually have metal rods in the long sides to keep them from sagging, but they also make it harder to get stuff in and out of then net. I think you can kind of see them in the Bekant pictures.
Otherwise maybe pick up some fabric of your choice and some 3-5mm elastic cord from a fabric store and bust out the sewing machine?