It looks like a leftover from the early dark ages of KiCad.
Would you want ERC errors if “GND” “Earth” and “GNDA” were connected together? Maybe net ties would have been appropriate here, but these are also still quite a hack in KiCad V5. It may have already changed in V5.99, or I will at least expect it to be implemented more logically in the future, and untill then, we’ll have to live with it.
See also this longish post I made for this new user, who had a more serious related problem.