Hypothetical driver stall in upscale pass

Apologies for the odd title but I was wondering if you could perhaps shed some light when it comes do driver-side behavior.
We're seeing some suspiciously high time "around" a single draw call - slightly above 2ms on a Mali-G72MP2 (Samsung A20). This represents an upscale pass (in Unity). I'd expect this to cost next to "nothing", CPU-wise, but I was wondering if what we're seeing could be related with the driver making sure the framebuffer that is being upscaled is fully resolved before the draw call and therefore stalling?

A simplified view of the GL calls would be:

glInvalidateFramebuffer( intermediateFBO ); // DEPTH and Stencil
glBindTexture( intermediateTexture); // the texture attached to intermediateFBO
glBindFramebuffer( backbuffer );
glInvalidateFramebuffer( backbuffer ); // COLOR
glDrawElements(); // the fullscreen quad

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