Fan speed oscillations in 1.10.x - bug or feature?

I'm aware that the jumps to 100% fan speed are meant to avoid pillowing but I always wondered if the wild "oscillations" on slopes were really meant to be this way.

What makes it even harder to believe that they are intentional is the fact that they only seem to happen for the highest resolutions (90µm and 140µm) and stop immediately with 190µm or higher.

3DBenchy, Z-ABS, default settings in 1.10, 140µm (looks the same for 90µm)

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fan_speed_benchy_140um.png

Very same models and settings, just the resolution changed to 190µm

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fan_speed_benchy_190um.png

As you can see, the profiles look identical apart from the oscillations. So is this really a feature that only affects the two highest resolutions or is there some software filter that is meant to detect slopes but fails for the high resolutions?

Just double checked it, has to be bug - reported, thanks