BUG: Surfaces incorrectly rendered on MacOS M1 (?)

[meag]

ezQuake version: ezquake 3.6-dev-alpha7 7069~21539784d

OS/device including version: MacOS m1 mini, classic

Describe the bug Triangles missing in the middle of surfaces

To Reproduce

1. Single player game > start
2. do not change angle using mouse
3. Walk forward off the steps onto the surface in front of the normal corridor
4. surface has triangle missing

Expected behavior Surfaces to be rendered as normal

Screenshots

Additional context Can reproduce with minimal opengl program attached gltest.zip. Can fix by rotating or by offsetting the x or z co-ordinates by tiny amounts (try keys 1/3/a/d when running program)

Rendering individual triangles or in the middle of a triangle strip doesn't make a difference, the triangle is culled. Have disabled face culling prior to rendering, no difference. Same commands on nvidia on windows renders a complete surface, as expected

[blaps]

Can reproduce on MacBook Pro (13-inch, M1, 2020), macOS 11.4 (20F71).