Can you send us a few things to help?

The output of nvidia-smi on your shell when you open a new terminal
The output of nvidia-smi on your coworker’s shell
the output of CUDA_VISIBLE_DEVICES=0,1,2,3 nvidia-smi on your coworker’s shell
the output nvidia-smi on your shell after they have run that
the output of CUDA_VISIBLE_DEVICES=0,1 nvidia-smi on your shell
the output of nvidia-smi on your coworker’s shell ofter you have run that?