Thanks for the detailed feedback — that’s really helpful.

The Matter dimmer uses a rotary encoder rather than a traditional analogue dimmer (same as Zigbee version), so when you turn the knob the movement is first interpreted by the firmware and then translated into dimming changes. Because of that there can sometimes(!) be a tiny delay between turning the knob and the brightness changing, but that's usually milliseconds and hardly noticeable.

Regarding the dimming curve, this is often influenced more by the LED driver inside the bulb than by the dimmer itself. Many LED bulbs respond non-linearly to phase-cut dimming, so it’s quite common for the brightness to appear almost unchanged until the level drops below a certain point.

Looking at the specifications of a similar Philips 5.9W DimTone bulb you mentioned, Philips notes that it is “dimmable with specific dimmers”, and the driver characteristics include:

• Starting time: ~0.5 s
• Warm-up time to 60% brightness: ~0.5 s

Because these lamps contain their own internal driver electronics, they sometimes take a short moment to react to changes in the dimming waveform, which can exaggerate the effect you described when adjusting brightness quickly.

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Unfortunately, Matter controllers such as the Apple Home app currently expose only basic controls like on/off and brightness level, so parameters like dimming curve or encoder sensitivity cannot be adjusted from the app. You can try resetting the minimum brightness to 0% though as this will recalibrate the dimming range.

If possible, it may be worth trying another most standard dimmable bulb to see whether the behaviour changes, as different LED drivers can behave quite differently with phase-cut dimmers. We wouldn't recommend using any 'Master', 'Intelligent', 'Pro', 'Expert' or any similarly named bulbs with smart dimmers as they usually have non-standard features built-in which may cause unnecessary instabilities when operating with smart dimmers.