Many Chinese tech giants already had A100 and maybe some H100 before the sanction. After the first wave of sanction (bans A100 and H100), NVIDIA released A800 and H800, which are nerfed versions of A100 and H100.
Then there was a second round of sanction that bans H800, A800, and all the way to much weaker cards like A6000 and 4090. So NVIDIA released H20 for China. H20 is an especially interesting card because it has weaker compute but larger vram (96 GB instead of the typical 80 GB for H100).
And of course they could have smuggled some more H100s.