Thanks for the report. This GPU is below the minimum requirements for Blender, so there is no longer support for it. https://www.blender.org/download/requirements/

Installing the latest graphics driver sometimes helps to make such GPUs work, see here for more information. https://docs.blender.org/manual/en/dev/troubleshooting/gpu/index.html
However, the only way to do that on a Apple product is by upgrading the OS, which you may not wish to do.

If that doesn't help, you can use an earlier version of Blender such as 2.79: https://www.blender.org/download/previous-versions/