It seems that the COP node "Bake Geometry Textures" on MacOS is not working. I get the error "Cannot allocate tracer 'optix'". In the parameter pane under "Tracer", "Embree v3.13.1" is selected and the only option. Is this a bug of H21?

It’s more likely a menu bug, and an old one at that. When a menu contains dynamic options, and only one option exists, and the default option is not in the list of options, the menu will show the only option as selected but really the invalid default is selected. This is usually worked around by opening the menu and clicking on the one option. Does that fix it? If not then it might be a bug in the node not respecting the chosen option. What does it say if you right click the parm and open the expression editor? Does it say “optix” or “embree”?

Ah yes, you're right. I can get it to work with your help! Clicking again on "Embree" does solve the issue! Many thanks for this!