Unexplained shader core utilization

Hi guys,

I'm seeing a peak in the shader core utilization which is not matched by any activity in the core unit utilization graph at all. My best guess for this is a series of OpenGL API calls that look inefficient to me (which I have below in pseudo-code):

glBindFramebuffer(fbo_1);
glInvalidateFramebuffer(fbo_1, {color,depth,stencil});
glClear(color|depth|stencil);
glBindFramebuffer(fbo_2);
...
// at some point
glBindFramebuffer(fbo_1);

Could the graph below explain this? I can barely see any writes (which, perhaps is related with transaction elimination?) so I'm pretty clueless. 

This was recorded in a Mali-G71 btw.

Cheers,

Joao