Blocky rendering of triangle with sRGB framebuffer

With the attached program that renders a single triangle on an sRGB enabled framebuffer gles.c, I'm seeing the result

Notice the lighter areas near the triangle edges.

If I comment out the

      glfwWindowHint(GLFW_SRGB_CAPABLE, 1);

line, the program draws correctly and renders without the blocky areas near edges.

I build the program with

gcc  -lglfw -lGLESv2 gles.c && ./a.out 

on a Fedora 31 machine.

Glxinfo: glxinfo